Electrode manufacturing system, electrode manufacturing method, and electrode

Abstract

An electrode manufacturing system according to an exemplary embodiment of the present invention includes a coating unit including a first coating unit that applies electrode slurry to a first surface of a current collector and a second coating unit that applies electrode slurry to a second surface of the current collector, an air injection unit, and a drying unit, the air injection unit being disposed on a transfer path between the second coating unit and the drying unit. The air injection unit can inject air into a fat edge of a second electrode active material layer caused by a sliding region of the first electrode active material layer formed on the first surface of the current collector, thereby moving the electrode slurry toward an uncoated portion and preventing the formation of the fat edge.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0128329, filed on September 25, 2023.

[0002] The present invention relates to a double-sided electrode having a structure in which electrode active material layers are laminated on both sides of a current collector, in which the occurrence of fat edges is prevented, and to a manufacturing system and method for such an electrode. [Background technology]

[0003] As technological development and demand for mobile devices, automobiles, energy storage devices, and other industrial fields increase, the demand for batteries as energy sources is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which have high energy density and discharge voltage, have been extensively researched and are now commercially available and widely used.

[0004] Depending on the shape of the battery case, secondary batteries are classified into cylindrical batteries and prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch batteries, in which the electrode assembly is housed in a pouch-shaped case made of an aluminum laminate sheet.

[0005] The electrode assembly housed in the battery case is a chargeable and dischargeable power generating element having a laminated structure of a positive electrode / separator / negative electrode. Examples of such an electrode assembly include a jelly-roll type electrode assembly in which a separator is interposed between a long sheet-shaped positive electrode and a negative electrode coated with an electrode mixture containing an electrode active material, and the electrode is wound up; a stack type electrode assembly in which a number of positive electrodes and negative electrodes that are punched and notched in predetermined sizes are sequentially stacked with a separator interposed; and a stack / folding type electrode assembly in which a bi-cell or full cell in which a predetermined number of positive electrodes and negative electrodes are stacked with a separator interposed is wound up.

[0006] The positive and negative electrodes that make up an electrode assembly are manufactured by applying electrode slurry, prepared in a mixing process, to an electrode current collector in a predetermined pattern and thickness through a slot die and then drying. During this electrode manufacturing process, fat edges, in which the electrode active material layer at both edges in the transverse direction (TD) of the electrode is thicker than the surrounding electrode active material layer, can form for various reasons. The presence of such fat edges in an electrode can damage the current collector during the rolling process, which can pose a safety hazard. Furthermore, during the process of stacking multiple positive and negative electrodes and separators, the fat edges can also damage other electrodes and separators. In particular, lithium can precipitate in a positive electrode that has a higher capacity than a negative electrode. However, fat edges can also cause a reversal of the NP ratio between the positive and negative electrodes, potentially posing a safety risk to the battery.

[0007] One method to prevent the occurrence of such fat edges is to readjust the width of the electrode slurry's horizontal spread (Y-axis direction) during the coating step, the distance between the slot die and the current collector, and the temperature of the electrode slurry. However, when this method is applied to mass production, it is troublesome to have to reset the above conditions to optimized conditions during the coating step. Furthermore, even if the above conditions are optimized, if problems such as changes in the electrode slurry over time occur, the spreading characteristics of the slurry will change, and accordingly the continuous process will have to be interrupted for a while and the conditions will have to be optimized again.

[0008] Therefore, there is a need to develop a technology for an electrode manufacturing system and method that can prevent the occurrence of fat edges without interrupting the electrode process. Summary of the Invention [Problem to be solved by the invention]

[0009] The problem to be solved by the technical idea of ​​the present invention is to provide an electrode, an electrode manufacturing system, and an electrode manufacturing method that prevent the occurrence of fat edges in a double-sided electrode having a structure in which electrode active material layers are laminated on both sides of a current collector. [Means for solving the problem]

[0010] According to one embodiment of the present invention, there is provided a system for manufacturing an electrode, the system including a coating unit including a slot die configured to discharge an electrode slurry and a coating roller disposed spaced apart from the slot die and configured to support a current collector, an air injection unit configured to inject air toward a periphery of a boundary between a coated portion and an uncoated portion of the electrode discharged from the coating unit, and a drying unit for drying the electrode slurry, the coating unit including a first coating unit that applies the electrode slurry to a first surface of the current collector and a second coating unit that applies the electrode slurry to a second surface of the current collector, and the air injection unit may be disposed on a transfer path between the second coating unit and the drying unit.

[0011] In one embodiment of the electrode manufacturing system, the electrode may be configured to be transported sequentially through the first coating section, the drying section, the second coating section, the air injection section, and the drying section.

[0012] In an electrode manufacturing system according to one embodiment, the air injection unit may be configured to inject air in a direction inclined with respect to an imaginary extension line of a flat surface of the landed portion.

[0013] In the electrode manufacturing system according to an embodiment, the air injection unit may be configured to be capable of adjusting the angle of the air injection direction.

[0014] The electrode manufacturing system according to one embodiment may further include a measuring unit configured to measure a coating amount of the electrode slurry applied to the ground portion, and an air injection unit controller configured to adjust an air injection angle, an air injection position, and an air injection intensity based on the coating amount received from the measuring unit.

[0015] In an electrode manufacturing system according to one embodiment, the measurement unit can be configured to calculate the coating amount of electrode slurry in real time based on X-ray absorptiometry.

[0016] In an electrode manufacturing system according to one embodiment, the measurement unit can be configured to calculate the coating amount of electrode slurry in real time based on the measured distance from the measurement position to the land portion.

[0017] In an electrode manufacturing system according to one embodiment, the measurement unit can be disposed downstream of the slot die of the second coating unit.

[0018] In an electrode manufacturing system according to one embodiment, the measurement unit can be configured to measure the vicinity of the boundary between the coated portion and the uncoated portion.

[0019] In an electrode manufacturing system according to one embodiment, the slot die can include two or more die blocks and a shim plate interposed between the die blocks to form a slot.

[0020] According to another embodiment of the present invention, there is provided a method for manufacturing an electrode, the method including: a first coating step of applying electrode slurry to a first surface of a current collector being transported; a first drying step of drying the electrode slurry applied to the first surface; a second coating step of applying electrode slurry to a second surface of the current collector being transported; a step of measuring the coating amount of the electrode slurry near the boundary between a coated portion and an uncoated portion; a step of determining whether or not a fat edge exists based on the measured coating amount; a step of spraying air onto the fat edge to remove the fat edge if it is determined that a fat edge exists; and a second drying step of drying the electrode slurry applied to the second surface.

[0021] In the electrode manufacturing method according to one embodiment, the electrode slurry may be a positive electrode slurry.

[0022] According to another embodiment, the present invention provides an electrode for a secondary battery, comprising the current collector and a first electrode active material layer and a second electrode active material layer formed on one side and the other side of the current collector, respectively, wherein the first electrode active material layer and the second electrode active material layer each have a first sliding region and a second sliding region that are inclined with respect to a plane of the current collector, and when the second electrode active material layer is superimposed on the first electrode active material layer rotated 180°, the inclined surface of the second sliding region may have a recess that is recessed inward relative to the inclined surface of the first sliding region.

[0023] The electrode may be a positive electrode. [Effects of the Invention]

[0024] According to an exemplary embodiment of the present invention, a double-sided electrode without a fat edge is provided by spraying air onto the fat edge of the second electrode active material layer caused by the sliding region of the first electrode active material layer formed on the first surface of the current collector, thereby moving the electrode slurry toward the uncoated area.

[0025] Furthermore, according to an exemplary embodiment of the present invention, it is only necessary to install an air injection unit configured to inject air toward the periphery of the boundary between the coated and uncoated portions of the electrode in a conventional electrode process line, thereby making it possible to manufacture electrodes without fat edges in a relatively easy manner, and there is no need to interrupt the electrode process, which is a continuous process, so there is an advantage in that production efficiency is not reduced. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram showing a method for manufacturing a double-sided electrode according to the prior art; [Figure 2] FIG. 1 is a cross-sectional view of an electrode having a fat edge. [Figure 3] 3 is a graph showing the results of measuring the thickness of an electrode active material layer located inside the dotted line in FIG. 2. [Figure 4] FIG. 1 is a schematic diagram of a double-sided electrode manufacturing system according to an exemplary embodiment. [Figure 5] FIG. 1 is a diagrammatical illustration of a double-sided electrode manufacturing system according to an illustrative embodiment; [Figure 6] FIG. 1 is an exploded perspective view of a slot die according to an exemplary embodiment. [Figure 7] FIG. 2 is a schematic diagram of an air injector according to an exemplary embodiment of the present invention. [Figure 8] 1 is a flowchart illustrating a method for manufacturing a double-sided electrode according to an exemplary embodiment. [Figure 9] 1 is a cross-sectional view of an electrode according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will now be described in more detail to aid in its understanding.

[0028] The terms and words used in this specification and claims should not be interpreted as being limited to their general or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best describe his / her own invention.

[0029] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise.

[0030] In this specification, terms such as "comprise," "comprise," or "have" are intended to specify the presence of implemented features, numbers, steps, components, or combinations thereof, and may be understood as not precluding the presence or possible addition of one or more other features, numbers, steps, components, or combinations thereof.

[0031] As used herein, the term "combinations thereof" in Markush expressions means a mixture or combination of one or more components selected from the group of components described in the Markush expressions, and means including one or more components selected from the group of components described above.

[0032] In this specification, the expression "A and / or B" means "A or B, or A and B."

[0033] In this specification, "%" means % by weight unless expressly indicated otherwise.

[0034] In this specification, the lateral direction TD of the current collector and electrode is defined as the Y-axis direction, the transport direction MD of the current collector and electrode is defined as the X-axis direction, the thickness direction of the electrode is defined as the Z-axis direction, and the X-axis and Y-axis directions are called horizontal directions.

[0035] In this specification, the coated portion is defined as a portion of the electrode substrate where the electrode slurry is applied, and the uncoated portion is defined as a portion of the electrode substrate where the electrode slurry is not applied and the current collector is exposed.

[0036] (First embodiment) The present invention provides a system for manufacturing an electrode as a first embodiment.

[0037] FIG. 4 is a schematic diagram of an electrode manufacturing system according to an exemplary embodiment, and FIG. 5 is a schematic diagram of an electrode manufacturing system according to an exemplary embodiment.

[0038] Referring to these drawings, an electrode manufacturing system according to an exemplary embodiment may include a coating unit 110, 110', an air injection unit 120, and a drying unit 130, 130'. The coating unit may be composed of a first coating unit 110 and a second coating unit 110', and the air injection unit 120 may be disposed on a transfer path between the second coating unit 110' and the drying unit 130'. That is, the air injection unit 120 is disposed on the transfer path between the second coating unit 110' and the drying unit 130', but is not disposed on the transfer path between the first coating unit 110 and the drying unit 130. The electrode manufacturing system is a system for manufacturing an electrode by applying an electrode slurry to a current collector 21 being transported in a roll-to-roll manner and drying the applied slurry.

[0039] The inventors of the present invention conducted long-term research into the cause of fat edge formation during the manufacture of double-sided electrodes, and discovered that fat edges mainly occur in the electrode active material layer on the back side of the current collector, leading to the present invention.

[0040] FIG. 1 is a diagram showing a method for manufacturing a double-sided electrode according to the prior art, FIG. 2 is a cross-sectional view of a double-sided electrode manufactured according to the prior art and having a fat edge, and FIG. 3 is a diagram showing the results of measuring the thickness of an electrode active material layer located inside the dotted line in FIG. 2.

[0041] According to a conventional double-sided electrode manufacturing method, a first electrode active material layer 12 is formed through a first coating step of applying electrode slurry to a first surface of a current collector 11, and then a second coating step of applying electrode slurry to a second surface of the current collector 11 is performed.

[0042] Referring to FIG. 1, both lateral (Y-axis) edges of the first electrode active material layer 12 formed in the first coating step include sliding regions 12S, where the end surfaces of the first electrode active material layer 12 are inclined relative to the plane of the current collector 11. The first electrode active material layer 12 including the sliding regions 12S faces the coating roller 112' in the second coating step. Because the sliding regions 12S are thinner than the non-sliding regions, the lateral (Y-axis) edges of the current collector 11 that contact the coating roller 112' have a slightly curved shape that follows the inclination angle of the sliding regions, as shown in FIG. 1. When electrode slurry is applied to the second surface of the current collector 11 in this state, the amount of electrode slurry applied near the point where the current collector 11 begins to bend slightly downward (arrow) may be greater than the amount of electrode slurry applied to the flat region of the current collector 11 parallel to the horizontal direction (Y-axis). As a result, the second electrode active material layer 13 in that area includes a fat edge that protrudes upward in the thickness direction (Z-axis direction) compared to the surrounding second electrode active material layer (see Figures 2 and 3).

[0043] As described above, since the thickness of the sliding region 12S of the first electrode active material layer 12 formed on the first surface of the current collector 11 is relatively small compared to the flat portion, in the second coating step, the current collector 11 of the electrode is slightly bent downward to follow the shape of the sliding region 12S of the first electrode active material layer 12. If the electrode slurry is applied to the current collector 11 in a bent-down state, a fat edge is generated that is flat relative to the electrode surface but where the thickness of the applied electrode slurry is thicker relative to the current collector plane than the flattened region.

[0044] According to an exemplary embodiment of the present invention, the air injection unit 120 is configured to inject air toward the sliding region of the electrode 20 being conveyed out of the second coating unit 110′, specifically toward the fat edge, and the electrode slurry in the area where the air is injected moves to the periphery due to the air injection pressure, thereby reducing the coating thickness of the electrode slurry in that area. As a result, fat edges are not generated at both side edges in the lateral direction (Y-axis direction) of the second electrode active material layer 23.

[0045] The coating units 110 and 110' may be configured to discharge electrode slurry onto the current collector 21 being transported in one direction. The coating units 110 and 110' apply the electrode slurry onto the current collector 21 to have a predetermined width, length, and thickness, and the applied electrode slurry passes through the drying units 130 and 130' to become the electrode active material layer 12.

[0046] The electrode slurry may be a mixture of an electrode active material, a binder, a conductive material, and a solvent, where the electrode active material may be a positive electrode active material or a negative electrode active material, the binder may be a polymer additive for structural stabilization of the electrode, and the conductive material may be a carbon-based additive having electrical conductivity.

[0047] The coating units 110 and 110' may include slot dies 111 and 111' configured to discharge electrode slurry, and coating rollers 112 and 112' spaced apart from the slot dies 111 and 111' to support the current collector sheet.

[0048] FIG. 6 is an exploded perspective view of a slot die according to an exemplary embodiment. Referring to FIG. 6, the slot die 111 may include two die blocks 111a and 111b and a shim plate 111c. The shim plate 111c may be interposed between the two die blocks 111a and 111b, which may be fastened to each other by a plurality of bolt members. At least one of the two die blocks may include a manifold 111d that contains a certain volume of electrode slurry, and the manifold 111d may be connected to an external electrode slurry supply unit (not shown).

[0049] 6 shows a slot die having two die blocks, the number of die blocks is not limited to this and may be two or more. Specifically, two die blocks may be required to apply a single electrode slurry, and three or more die blocks may be required to apply two or more electrode slurries. That is, the number of die blocks may be two or more.

[0050] The coating rollers 112 and 112′ may be configured to support and transport the current collector 21 in a transport direction when the electrode slurry is discharged from the slot dies 111 and 111′. The coating rollers 112 and 112′ may be disposed below the slot dies 111 and 111′ at a distance from the current collector 21.

[0051] The coating units 110, 110' may be composed of a first coating unit 110 that applies electrode slurry to a first surface of the current collector 21 and a second coating unit 110' that applies electrode slurry to a second surface of the current collector 21 in order to manufacture a double-sided electrode having an electrode active material layer stacked on both surfaces of the current collector 21. The second coating unit 110' is different from the first coating unit 110 only in its installation position, but the type and application method of the electrode slurry applied to the current collector 21 are the same.

[0052] The drying unit 130 is configured to apply heat energy to the electrode slurry coated on the current collector 21, thereby drying the electrode slurry. To dry a double-sided electrode having an electrode active material layer stacked on both sides of the current collector 21, the drying unit 130 may include a first drying unit 130 that dries the electrode slurry coated on the first side of the current collector 21, and a second drying unit 130' that dries the electrode slurry coated on the second side of the current collector 21. The second drying unit 130' may be installed in the same position as the first drying unit 130, but may use the same drying method.

[0053] The drying units 130, 130' may include a drying means, which may include a hot air supply unit configured to spray hot air toward the electrode slurry coated on the current collector 21 and / or a heater configured to radiate radiant heat. The current collector onto which the electrode slurry is coated passes through the drying units 130, 130', and the electrode is dried by the thermal energy applied by the drying means.

[0054] The air injection unit 120 may be configured to inject air toward a sliding region, more specifically, a fat edge, of the electrode 20 being conveyed out of the second coating unit 110'.

[0055] FIG. 7 is a schematic diagram of an air injector according to an exemplary embodiment of the present invention.

[0056] 4 to 5 and 7, the air injection unit 120 can inject air toward the fat edge portion of the electrode 20 to move the electrode slurry at the fat edge to the periphery in order to reduce the thickness of the fat edge at the width direction (Y-axis direction) edge of the second electrode active material layer 23 formed on the second surface of the current collector 21.

[0057] After the electrode slurry is completely dried, it is difficult for the electrode slurry to move toward the uncoated area by air injection, so it is preferable that the air injection unit 120 be disposed before the electrode 20 is introduced into the second drying unit 130'.

[0058] In one embodiment, the air injection unit 120 may be disposed on a transfer path between the second coating unit 110' and the second drying unit 130'. Here, the transfer path between the second coating unit 110' and the second drying unit 130' includes both the transfer path of the second coating unit 110' and the transfer path between the second coating unit 110' and the front end of the second drying unit 130'.

[0059] The transfer path of the second coating unit 110' may refer to a transfer path close to the slot die 111' and a transfer path until the electrode 20 is carried out from the coating roller 112'.

[0060] The transport path between the second coating unit 110' and the front end of the second drying unit 130' may refer to the transport path after the electrode 20 is conveyed from the coating roller 112' and before it is introduced into the second drying unit 130'.

[0061] As a result, in the electrode manufacturing system 100 of the present invention, the electrode 20 can be transported sequentially through the first coating section 110, the first drying section 130, the second coating section 110', the air injection section 120, and the second drying section 130'.

[0062] Referring to FIG. 7 , in one embodiment, the air injection unit 120 may include an air pipe 121, a nozzle 122, and an air supply unit (not shown). The air supply unit may be configured to supply compressed air to the air pipe 121. The air pipe 121 may be a pipe through which air flows. The air pipes 121 may be arranged side by side in the width direction (Y-axis direction) of the electrode. At least one nozzle 122 may be installed in the air pipe 121. At least one nozzle 122 may include a nozzle valve (not shown). By opening and closing each nozzle valve, air flowing through the air pipe can be sprayed to the outside through the nozzle. In addition, the amount of sprayed air can be adjusted depending on the degree of opening and closing of the nozzle valve.

[0063] 5, in one embodiment, the air injection unit 120 may be configured to inject air in a direction inclined with respect to an imaginary extension of the flat surface of the land area, thereby allowing the electrode slurry in the relatively thickly applied area to be moved to the periphery by the high-pressure air injected from the air injection unit 120.

[0064] In addition, the air injection unit 120 may be configured to be capable of adjusting the angle of the air injection direction, thereby making it possible to appropriately adjust the direction of the injected air.

[0065] Referring to FIG. 7, the air injection units 120 may be arranged on both side edges along the width direction (Y-axis direction) of the electrode 20, or two or more air injection units 120 may be arranged spaced apart along the transfer direction (X-axis direction) of the electrode 20.

[0066] The electrode manufacturing system 100 according to one embodiment may further include a measuring unit (not shown) configured to measure the coating amount of the electrode slurry applied to the ground portion, and an air injection unit controller (not shown) configured to adjust the air injection angle, the air injection position, and the air injection intensity based on the coating amount received from the measuring unit.

[0067] In one embodiment, the measuring unit may be configured to measure in real time the coating amount of electrode slurry near the boundary between the coated and uncoated areas. Here, the vicinity of the boundary between the coated and uncoated areas refers to both side edges in the width direction (Y-axis direction) of the second electrode active material layer 23 formed from the electrode slurry applied to the second surface of the current collector 21. Since a fat edge occurs near the boundary between the coated and uncoated areas, specifically, from a point where the thickness of the electrode active material layer begins to decrease in the width direction (Y-axis direction) of the electrode, the measuring unit is configured to measure the vicinity of the boundary between the coated and uncoated areas.

[0068] The measurement unit can be configured to measure the coating amount of electrode slurry on the electrode edge in real time and send measurement information to the air injection unit controller so that air injection conditions such as the air injection angle, air injection position, and air injection intensity can be optimized when the air injection unit 120 injects air.

[0069] The air injection unit controller can be configured to determine whether or not fat edges exist on both side edges in the width direction of the electrode 20 based on the measurement information received in real time. The presence or absence of fat edges can be determined by comparing the measurement information received from the measurement unit with a preset coating amount or a preset thickness of the electrode active material layer at the edge in the width direction (Y-axis direction) of the electrode active material layer.

[0070] Furthermore, the air injection unit controller may be configured to determine, based on the measurement information received in real time, one or more of the air injection angle, air injection position, and air injection intensity of the air injected from the air injection unit to an appropriate level in order to reduce the coating amount of electrode slurry or the applied thickness of the electrode slurry where the fat edge is present. To this end, appropriate air injection conditions according to the coating amount of electrode slurry or the applied thickness of the electrode slurry where the fat edge is present may be input in advance to the air injection unit controller.

[0071] In one embodiment, the measuring device may be configured to calculate the coating amount of the electrode slurry in real time based on an X-ray absorption method. An example of such a measuring unit is a web gauge.

[0072] In another embodiment, the measurement unit may be configured to calculate the coating amount of the electrode slurry in real time based on the measured distance from the measurement position to the land area. An example of such a measurement unit is a confocal sensor.

[0073] The location of the measuring unit is not particularly limited, but it is preferably installed in the second coating unit or downstream thereof, where the occurrence of fat edges can be confirmed. Specifically, it is preferably installed downstream of the slot die 111' of the second coating unit 110'. However, the location is not limited thereto, and the measuring unit may be installed downstream of the second coating unit, on the transport path at the front end of the second drying unit, or downstream of the second drying unit.

[0074] The electrode manufacturing system 100 according to one embodiment may include an unwinder unit 150 disposed at the front end of the first coating unit 110 and supplying a current collector 21 to the first coating unit 110, and a rewinder unit 170 disposed at the rear end of the second drying unit 130′ and winding up the electrode 20 after the electrode slurry coating and drying are complete. The current collector 21 in the form of a metal foil may be supplied to the unwinder unit 150 in a wound state. The supplied current collector may be sequentially passed through the first coating unit 110, the first drying unit 130, the second coating unit 110′, the air injection unit 120, and the second drying unit 130′, and then wound up by the rewinder unit 170. The electrode after the double-side coating and drying of the electrode slurry is wound up by the rewinder unit 170 and then passed through a slitting unit or a punching unit, which is the next step, to be manufactured as an electrode.

[0075] An electrode manufacturing system according to one embodiment may include a conveyor line that continuously transports the electrode current collector 21 from when it is supplied from the unwinder unit 150 until it is wound up by the rewinder unit 170. The conveyor line may be configured to continuously supply and transport the electrode current collector 21, so that the electrode current collector 21 passes through the first coating unit 110, the first drying unit 130, the second coating unit 110′, the air injection unit 120, and the second drying unit 130′ in sequence.

[0076] (Second embodiment) The present invention provides a method for producing an electrode as a second embodiment.

[0077] FIG. 8 is a flowchart illustrating a method for manufacturing an electrode according to an exemplary embodiment.

[0078] Referring to FIG. 8, an exemplary embodiment of a method for manufacturing an electrode includes a first coating step (P110) of applying electrode slurry to a first surface of a current collector being transported, a first drying step (P120) of drying the electrode slurry applied to the first surface, a second coating step (P130) of applying electrode slurry to a second surface of the current collector being transported, a step (P140) of measuring the coating amount of the electrode slurry near the boundary between the coated and uncoated portions, a step (P150) of determining whether a fat edge exists based on the measured coating amount, a step (P160) of spraying air onto the fat edge to remove the fat edge if it is determined that a fat edge exists, and a second drying step (P170) of drying the electrode slurry applied to the second surface.

[0079] An exemplary embodiment of an electrode manufacturing method measures the coating amount of electrode slurry applied to the second surface of a current collector in real time, and determines whether a fat edge will occur on the edge of the electrode in the width direction (Y-axis direction) based on the measured coating amount information.If it is determined that a fat edge has occurred, air is sprayed onto the fat edge to remove the fat edge, thereby causing the electrode slurry at the fat edge to spread toward the uncoated area, thereby preventing the formation of the fat edge.

[0080] In addition, in an electrode manufacturing process in which the electrode slurry coating step and drying step are performed consecutively, the generation of fat edges at the widthwise edges of the electrode can be prevented without immobilizing the process, thereby improving production efficiency.

[0081] The electrode manufacturing method according to one embodiment can be performed by the electrode manufacturing system 100 described above.

[0082] The first coating step P110 and the second coating step P130 can be performed by the first coating unit 110 and the second coating unit 110', respectively; the first drying step P120 and the second drying step P170 can be performed by the first drying unit 130 and the second drying unit 130', respectively; the step P140 of measuring the coating amount can be performed by the measuring unit; the step P150 of determining whether a fat edge exists can be performed by the air injection unit controller; and the step P160 of injecting air onto the fat edge can be performed by the air injection unit.

[0083] The specific contents of the first coating step P110 to the second drying step P170 have been explained in detail above, so a duplicate explanation will be omitted.

[0084] (Third embodiment) The present invention provides an electrode for a lithium secondary battery as a third embodiment.

[0085] FIG. 9 is a cross-sectional view of an electrode according to an exemplary embodiment.

[0086] Referring to Figure 9, an electrode 20 according to an exemplary embodiment is an electrode including a current collector 21 and a first electrode active material layer 22 and a second electrode active material layer 23 formed on a first surface and a second surface of the current collector 21, respectively, wherein the first electrode active material layer 22 includes a first sliding region 22S that is inclined with respect to the plane of the current collector 21, and the second electrode active material layer 23 includes a second sliding region 23S that is inclined with respect to the plane of the current collector 21.

[0087] The first electrode active material layer is formed from an electrode slurry applied to the first surface of the current collector, and the second electrode active material layer is formed from an electrode slurry applied to the second surface of the current collector. After the second coating unit applies the electrode slurry to the second surface of the current collector as described above, the air injection unit injects high-pressure air into the area where the electrode slurry is applied and where fat edges are expected to occur, specifically, into both side edges in the lateral direction (Y). At this time, the area where the air is injected into the electrode slurry application unit may have a concave shape due to the air pressure.

[0088] Therefore, the shape of the second sliding region formed through the air injection process is different from the shape of the first sliding region formed without the air injection process. Specifically, when the second electrode active material layer and the first electrode active material layer rotated 180° are superimposed on each other, the inclined surface of the second sliding region 23S may have a recess 23SR that is recessed from the inclined surface of the first sliding region 22S.

[0089] When the electrode is a positive electrode, if the sliding region includes a recess, the capacity of the sliding region facing the negative electrode is reduced, which has the advantage of reducing the risk of reversing the NP ratio at that location.

[0090] In one embodiment, the lateral direction (TD, Y direction) length y of the second electrode active material layer 23 may be 0.99 to 1.01, preferably 1, of the lateral direction length x of the first electrode active material layer 22. The electrode is designed to have the same value of y and the same value of x during manufacturing, but depending on tolerances, y may be in the range of 0.99 to 1.01 of x. In addition, it is preferable that the thickness T2 of the second electrode active material layer 23 and the thickness T1 of the first electrode active material layer are the same.

[0091] In one embodiment, the angle b formed by the inclined surface of the second sliding region 23S and the plane of the current collector 21 may be 0.99 to 1.01, preferably 1, of the angle a formed by the inclined surface of the first sliding region 22S and the plane of the current collector 21. The electrode is designed to have the same value of b and the same value of a during manufacturing, but depending on tolerances, the value of b may be in the range of 0.99 to 1.01 of the value of a.

[0092] In one embodiment, the lateral length d of the second sliding region 23S may be 0.99 to 1.01 of the lateral length c of the first sliding region 22S, preferably 1. The electrode is designed to have the same value of d and the same value of c during manufacturing, but depending on tolerances, d may be in the range of 0.99 to 1.01 of c.

[0093] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations shown in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore, at the time of filing this application, there may be various equivalents and modifications that can replace them. [Explanation of symbols]

[0094] 10, 20: Electrode 11, 21: Current collector 12, 22: First electrode active material layer 13, 23: Second electrode active material layer 100: Electrode manufacturing system 110: First coating section 110': Second coating section 120: Air injection unit 130:Drying section

Claims

1. a coating unit including a slot die configured to discharge an electrode slurry and a coating roller disposed apart from the slot die and for supporting a current collector; an air injection unit configured to inject air toward the periphery of the boundary between the coated portion and the uncoated portion of the electrode conveyed from the coating unit; a drying section for drying the electrode slurry; An electrode manufacturing system comprising: the coating unit includes a first coating unit that applies electrode slurry to a first surface of the current collector, and a second coating unit that applies electrode slurry to a second surface of the current collector; The system for manufacturing an electrode, wherein the air injection unit is disposed on a transfer path between the second coating unit and the drying unit.

2. The electrode manufacturing system according to claim 1 , wherein the electrode is transported through the first coating section, the drying section, the second coating section, the air injection section, and the drying section in this order.

3. The electrode manufacturing system according to claim 1 , wherein the air injection unit is configured to inject air in a direction inclined with respect to an imaginary extension line of a flat surface of the landed portion.

4. The electrode manufacturing system according to claim 1 , wherein the air injection unit is configured to be able to adjust the angle of the air injection direction.

5. a measuring unit configured to measure a coating amount of the electrode slurry applied to the ground portion; an air injection unit controller configured to adjust an air injection angle, an air injection position, and an air injection intensity based on the coating amount received from the measurement unit; The system for manufacturing an electrode according to claim 1 , further comprising:

6. The electrode manufacturing system according to claim 5 , wherein the measurement unit is configured to calculate the coating amount of the electrode slurry in real time based on an X-ray absorptiometry method.

7. The electrode manufacturing system according to claim 5 , wherein the measurement unit is configured to calculate a coating amount of electrode slurry in real time based on a measured distance from a measurement position to the land portion.

8. The electrode manufacturing system according to claim 5 , wherein the measurement unit is disposed downstream of the slot die of the second coating unit.

9. The electrode manufacturing system according to claim 5 , wherein the measurement unit is configured to measure a vicinity of a boundary between the coated portion and the uncoated portion.

10. The slot die is two or more die blocks; a shim plate interposed between the die blocks and defining a slot; The electrode manufacturing system of claim 1 , comprising:

11. a first coating step of applying an electrode slurry to a first surface of the transported current collector; a first drying step of drying the electrode slurry applied to the first surface; a second coating step of applying an electrode slurry to a second surface of the transferred current collector; measuring the coating amount of the electrode slurry near the boundary between the coated portion and the uncoated portion; determining whether a fat edge exists based on the measured coating amount; If a fat edge is determined to be present, spraying air onto the fat edge to remove the fat edge; a second drying step of drying the electrode slurry applied to the second surface; A method for manufacturing an electrode, comprising:

12. The method for producing an electrode according to claim 11 , wherein the electrode slurry is a positive electrode slurry.

13. An electrode comprising a current collector, and a first electrode active material layer and a second electrode active material layer formed on one surface and the other surface of the current collector, respectively, the first electrode active material layer and the second electrode active material layer each include a first sliding region and a second sliding region that are inclined with respect to a plane of the current collector; An electrode, wherein when the second electrode active material layer is superimposed on a first electrode active material layer rotated 180 degrees, the inclined surface of the second sliding region has a recess that is recessed inward relative to the inclined surface of the first sliding region.

14. 14. The electrode of claim 13, wherein the electrode is a positive electrode.

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