Electrode, manufacturing method therefor, and slot die for coating active material

Abstract

The present invention relates to a slot die for coating an active material layer on a foil, an electrode manufacturing method for manufacturing an electrode by using the slot die, and an electrode manufactured using the slot die. According to the present invention, the slot die is configured to move relative to the foil in the width direction.

Description

Electrode, method for manufacturing the same, and slot die for coating active material

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0100538, dated July 29, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a slot die for coating an active material layer on a foil, an electrode manufacturing method for manufacturing an electrode using the same, and an electrode manufactured using the same.

[0003] Secondary batteries, which have high applicability according to product group and electrical characteristics such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by electrical power sources.

[0004] These secondary batteries are attracting attention as a new energy source for environmental friendliness and energy efficiency because they not only have the primary advantage of drastically reducing the use of fossil fuels, but also have the advantage of producing no byproducts from energy use.

[0005] Currently, the types of secondary batteries widely used include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of these unit secondary battery cells, i.e., unit battery cells, is approximately 2.5 V to 4.5 V. Therefore, when a higher output voltage is required, multiple battery cells are connected in series to form a battery pack. Furthermore, depending on the charge / discharge capacity required for the battery pack, a number of battery cells are connected in parallel to form a battery pack. Therefore, the number of battery cells included in the battery pack and the electrical connection type can be set in various ways depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, known types of unit secondary battery cells include cylindrical, prismatic, and pouch-shaped battery cells. Among these, pouch-shaped batteries typically include a stacked electrode assembly in which multiple electrodes cut to a certain width are laminated with a separator interposed between them. Each electrode comprises a metallic foil and an active material layer applied to both sides of the foil.

[0007] Fig. 1 shows a slot die coating an active material layer on a foil, and Fig. 2 shows an electrode formed by slitting the foil of Fig. 1. Referring to these drawings, the electrode (1) is formed by coating an active material slurry discharged from a slot die (2) on both sides of a foil (10) that is unwound from a foil roll (100) and continuously supplied, and then coating an active material layer (11) on the foil, and then slitting the foil at a predetermined interval in the longitudinal direction.

[0008] At this time, the surface of the foil (10) is not coated with the active material layer (11) over its entirety, but forms a non-coated portion (12) along one end of its width direction where the active material slurry is not coated. The non-coated portion (12) is later subjected to a notching process to form a tab for electrically connecting each electrode (1) to a terminal.

[0009] Fig. 3 is a cross-sectional view showing an enlarged portion of the non-coated side end of the active material layer in the electrode of Fig. 2. Referring again to Fig. 1, a sliding portion (110) may be formed in the portion of the active material layer (11) corresponding to the longitudinal ends of the slot die (2) by the flow of the active material slurry. This sliding phenomenon causes the thickness of the active material layer (11) to gradually become thinner as it goes toward the ends, making the coating area and thickness of the active material layer (11) uneven. This unevenness has a negative impact on the charge / discharge efficiency and stability of the entire battery.

[0010] In addition, the active material layer (11) coated on the foil (10) as described above is generally flattened through a rolling step, but the sliding portion (110) formed to be thinner than the remaining portions is not properly pressured during the rolling process and cannot be flattened with the remaining portions.

[0011] In addition, if the coating area and thickness of the active material layer (11) are not uniform, the adhesion between the separator and the electrode (1) due to the binder contained in the active material slurry and the binder coated on the surface of the separator may be weakened. Accordingly, the fixing force between the electrode (1) and the separator may be weakened, and the structural stability of the electrode assembly may be significantly reduced. In particular, if the fixing force between the electrode (1) and the separator is weak on the non-coated side where the tab is provided, the active material layer (11) is easily exposed to the outside and there is a very high risk of causing a short circuit by coming into contact with the tab. If a short circuit occurs in the electrode assembly, this may lead to an explosion or fire, and thus, this can be said to be a very serious risk to the safety of the battery.

[0012] The present invention was created under the background of the above-described prior art, and aims to provide a structure of an electrode having a constant thickness and coating area of ​​an active material layer and stable charge / discharge performance, and a method for manufacturing the same.

[0013] In addition, the present invention seeks to provide a method for manufacturing an electrode that prevents uneven rolling caused by a sliding phenomenon.

[0014] Another technical problem of the present invention is to provide a structure of an electrode and a method for manufacturing the same, in which the adhesion between the separator and the electrode is improved and short circuit is prevented.

[0015] The technical objectives of the present invention are not limited to the purposes mentioned above. Other objectives and advantages of the present invention not mentioned above can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0016] In order to solve the above problem, the present invention provides a method for manufacturing an electrode, including a coating step, in which an active material slurry is applied to both sides of a foil that is unwound from a foil roll and runs with a predetermined first width to coat an active material layer, wherein the active material layer is coated on a portion excluding a non-coated portion extending along one end of the width direction of the foil with a predetermined second width.

[0017] According to the present invention, in the coating step, the coating of the active material layer is performed by a slot die that moves relative to the foil in the width direction and discharges the active material slurry.

[0018] According to the present invention, since sliding does not occur at the non-conductive end of the active material layer, the adhesive force between the electrode and the separator is strengthened, the charge / discharge performance is stable, and the risk of short circuit can be reduced.

[0019] According to one embodiment, the active material slurry may be discharged when the slot die moves relative to the first width direction, and may not be discharged when the slot die moves relative to the second width direction. That is, the slot die moves back and forth relative to the foil in both width directions, but the active material slurry may be discharged only in one direction.

[0020] According to one variation, the active material slurry can be discharged both when the slot die moves in the first width direction and the second width direction. That is, the slot die moves reciprocally in both width directions relative to the foil, and the discharge of the active material slurry can also be performed in both directions.

[0021] The electrode manufacturing method according to the present invention may further include, after the coating step, a slitting step of cutting the foil along a cutting line extending in the width direction at a first length interval to form an electrode. At this time, it is preferable that the discharge slit of the slot die extends by a second length that is greater than the first length. If the second length is shorter than the first length, a sliding portion may be located between a pair of adjacent cutting lines, and thus this can be prevented by making the second length greater than the first length.

[0022] Specifically, it is preferable that the second length be at least twice the first length. In this case, two or more electrodes that do not include a sliding portion can be obtained from an area once coated by the slot die.

[0023] In one embodiment, in the slitting step, the cutting line is preferably positioned at a portion where the active material layer is continuously coated on both sides in the longitudinal direction. In this case, the longitudinal ends of the electrode can be formed flat without sliding, thereby improving adhesion to the separator, ensuring stable charge / discharge performance, and preventing short circuits.

[0024] The electrode manufacturing method according to the present invention may additionally include, after the coating step, a rolling step of flattening the foil by rolling it in the thickness direction.

[0025] According to one embodiment, in the coating step, an overlapping portion in which the active material layer is double-coated or more may be formed in at least some areas extending in the width direction on both sides of the foil.

[0026] Specifically, the overlapping portion can be formed by overlapping the first coating area of ​​the slot die and the second coating area immediately thereafter by a predetermined length.

[0027] In one embodiment, the overlapping portion may be formed thicker than the remaining portion of the active material layer and may be flattened during the rolling step. Accordingly, the active material layer may be formed continuously and flat along the longitudinal direction without uneven rolling due to sliding.

[0028] According to another embodiment, in the coating step, a raised portion may be formed in which the active material layer is coated thicker than the remaining portion in at least some areas extending in the width direction on both sides of the foil.

[0029] The above-mentioned raised portion may be formed at a portion corresponding to a longitudinal end of the discharge slit of the slot die. Accordingly, even if sliding occurs in the active material layer at a portion corresponding to the longitudinal end of the discharge slit, the thickness thereof may be formed thicker than that of the remaining portion of the active material layer. The raised portion formed so thickly may be flattened during the rolling step. Accordingly, the active material layer may be continuously formed flat along the longitudinal direction without uneven rolling due to sliding.

[0030] In the coating step according to one embodiment, a raised portion may be formed on at least one of the widthwise ends of the active material layer, in which the active material layer is coated more thickly along the lengthwise direction than the remaining portion. The raised portion may be formed by additionally discharging the active material slurry while the slot die is temporarily stationary before and / or after the slot die begins to move relative to the foil in the widthwise direction.

[0031] For example, when the slot die starts coating from the non-coated portion side, the slot die may form the raised portion by discharging the active material slurry for a predetermined period of time in a stationary state and then start relative movement to perform coating on the remaining portion. Alternatively, the slot die may form the raised portion by discharging the active material slurry in a stationary state from the widthwise end of the foil and coating the active material layer, and then reaching the boundary of the non-coated portion side of the active material layer and then stopping for a moment.

[0032] The above-mentioned raised portion is preferably formed along the non-coated end of the active material layer. Accordingly, even if sliding occurs at the non-coated end of the active material layer, the thickness thereof can be formed thicker than that of the remaining portion of the active material layer. The raised portion formed thickly in this manner can be flattened during the rolling step, thereby improving the adhesive strength between the electrode and the separator, the stability of charge / discharge performance, and the safety against short circuits.

[0033] The present invention also provides a slot die for coating an active material layer by applying an active material slurry on both sides of a foil that is rolled and unwound from a foil roll having a predetermined width, the slot die having a structure including a discharge slit extending in the longitudinal direction through which the active material slurry is discharged.

[0034] The above foil may be configured to move relative to the width direction and discharge the active material slurry. The electrode manufacturing method according to the above embodiment may be performed using a slot die having the above-described structure.

[0035] An extension portion having a larger width than the remaining portion may be formed at both longitudinal ends of the discharge slit. The electrode manufacturing method according to the other embodiment can be performed using a slot die having the extension portion as described above. Specifically, the extension portion has a larger width and forms a larger discharge cross-sectional area per unit length, so that the active material slurry can be discharged at a larger flow rate even under the same pressure as the remaining portion. Accordingly, the thickness of the active material layer in the portion corresponding to the extension portion becomes relatively large, and a raised portion having a thicker thickness than the remaining portion may be formed in the portion corresponding to the longitudinal ends of the discharge slit in the active material layer.

[0036] The present invention also provides an electrode structure comprising a foil; an active material layer coated on both sides of the foil; a non-coated portion extending longitudinally along one widthwise end of the foil and not coated with the active material layer; and an insulating layer including a cover portion covering the active material layer and an attachment portion attached to the non-coated portion, as a result of performing the above electrode manufacturing method.

[0037] According to the present invention, the cover part may include an arch part having an arch shape that is convex toward the non-coated portion. The arch part may be formed by forming the raised portion at the end of the non-coated portion of the active material layer, and rolling the electrode while the cover part covers the raised portion. More specifically, while the inner end of the attachment part is firmly attached to the foil, the raised portion is rolled and protrudes in a horizontal direction, so that the cover part also forms the arch part that protrudes toward the non-coated portion.

[0038] According to the present invention, an electrode structure is provided in which an end portion of an active material layer is formed flat, thereby preventing insufficient attachment of an electrode and a separator due to sliding, a risk of short circuit, and instability of charge / discharge performance due to unevenness of the active material layer.

[0039] The present invention can provide a structure of an electrode having stable charge / discharge performance and a manufacturing method thereof, in which a sliding portion is not formed, an overlapping portion and / or a raised portion is formed, or the middle portion of a coating area is slit, thereby ensuring a constant thickness and application area of ​​an active material layer.

[0040] In addition, the present invention provides a method for manufacturing an electrode in which rolling unevenness due to sliding is prevented by thickening the area where sliding may occur.

[0041] Another advantage of the slot die, electrode manufacturing method, and / or electrode manufactured using the same according to the present invention is that the adhesion between the separator and the electrode is improved and short circuit is prevented due to the uniform thickness of the active material layer.

[0042] In addition, the present invention may have various other effects, which will be described in each embodiment, or the description of effects that can be easily inferred by a person skilled in the art will be omitted.

[0043] Figure 1 shows a slot die coating an active material layer on a foil.

[0044] Fig. 2 shows an electrode formed by slitting the foil of Fig. 1.

[0045] Fig. 3 is a cross-sectional view showing an enlarged portion of the non-conductive side end of the active material layer in the electrode of Fig. 2.

[0046] Figure 4 shows a method for manufacturing an electrode according to one embodiment.

[0047] Figure 5 illustrates a coating step according to one embodiment.

[0048] Figure 6 shows a coating step according to one modified example.

[0049] Fig. 7 shows a cross-section of an overlap portion according to one embodiment.

[0050] Figures 8 and 9 show how the overlap portion is flattened in the rolling step according to one embodiment.

[0051] Figure 10 shows a coating step according to another embodiment.

[0052] Fig. 11 shows a cross-section of a raised portion according to another embodiment.

[0053] Figures 12 and 13 show how the raised portion is flattened in the rolling step according to another embodiment.

[0054] Figure 14 illustrates a slitting step according to one embodiment.

[0055] Figure 15 shows an electrode without an insulating layer coating according to one embodiment.

[0056] Figures 16 and 17 show the appearance of the electrode of Figure 15 before and after the rolling step, respectively.

[0057] Fig. 18 shows an electrode coated with an insulating layer according to one embodiment.

[0058] Figures 19 and 20 show the appearance of the electrode of Figure 18 before and after the rolling step, respectively.

[0059] [Explanation of symbols]

[0060] 1: Electrode 10: Foil 100: Foil roll 11: Active material layer 110: Sliding portion 111: Overlap portion 112: Raised portion 113: Raised portion 11a: First coating area 11b: Second coating area 3 12: Non-coated portion 13: Insulating layer 130: Attachment portion 131: Cover portion 132: Arch portion 2: Slot die 20: Discharge slit 200: Expansion portion 3: Rolling roller 4: Cutting line W1~2: First~Second width L1~2: First~Second length RD: Traveling direction

[0061] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0062] Although the terms "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used solely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0063] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0064] Hereinafter, the phrase "any configuration is placed on (or below)" a component or "on (or below)" a component may mean that any configuration is placed in contact with the upper surface (or lower surface) of said component, and that other configurations may be interposed between said component and any configuration placed on (or below) said component.

[0065] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component.

[0066] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consisting of" or "comprising" should not necessarily be construed to include all of the components or steps described in the specification, and should be construed to mean that some of the components or steps may not be included, or that additional components or steps may be included.

[0067] Throughout the specification, when we refer to "A and / or B", this means A, B, or A and B, unless otherwise stated, and when we refer to "C to D", this means C or more and D or less, unless otherwise stated.

[0068] Hereinafter, a preferred embodiment of the present invention will be described with reference to the attached drawings.

[0069] Figure 4 illustrates an electrode manufacturing method according to one embodiment. Referring to this, the electrode manufacturing method according to one embodiment of the present invention includes a coating step (S1) in which a slot die coats an active material layer on a foil, a rolling step (S2) in which a rolling roller rolls the foil coated with the active material layer, and a slitting step (S3) in which the rolled foil is slit into predetermined length intervals. Hereinafter, the performance process of each step, the equipment used therefor, and the structure of the resulting electrode will be described in detail.

[0070] Figure 5 illustrates a coating step according to one embodiment. Referring to this, the coating step (S1) is performed by the slot die (2) discharging an active material slurry onto the foil (10) that is unwound from a foil roll (100), continuously supplied, and running along the longitudinal direction. The slot die (2) is equipped with a discharging slit (20) that discharges the active material slurry and applies it to the surface of the foil (10).

[0071] The above foil (10) may have a first width (W1). At this time, a non-coated portion (12) extending to a second width (W2) and not coated with the active material layer (11) is formed on the foil (10). The non-coated portion (12) may form a tab for connecting the electrode assembly to the outside through a notching process at a later time.

[0072] The above slot die (2) has a shape extending in the longitudinal direction or the running direction of the foil (10), and the same applies to the discharge slit (20). The slot die (2) is configured to be able to reciprocate relative to the foil (10) in the width direction. At this time, the slot die (2) moves relative to the surface of the foil (10) in the width direction and discharges the active material slurry through the discharge slit (20), thereby coating the active material layer (11) on the foil (10).

[0073] According to one embodiment, the slot die (2) is configured to reciprocate in a first width direction and a second width direction opposite to the first width direction with respect to the foil (10). At this time, the slot die (2) is configured to discharge the active material slurry when it moves relative to the first width direction, and not to discharge the active material slurry when it moves relative to the second width direction, so that the coating of the active material layer (11) can be performed in only one direction to have high coating consistency.

[0074] Fig. 6 illustrates a coating step according to one variation. Referring to this, the slot die (2) according to one variation can discharge the active material slurry both when moving in the first width direction and the second width direction. That is, the slot die (2) moves back and forth relative to the foil (10) in both width directions, and the discharge of the active material slurry can also be performed in both directions. This increases the line efficiency of the slot die (2), thereby allowing the running speed of the foil (10) to also increase, which is more preferable in terms of the speed and efficiency of the process.

[0075] According to the present invention, as the slot die (2) coats the active material layer (11) along the width direction of the foil (10), the sliding phenomenon of the active material layer (11) also occurs mainly at the longitudinal end of the coating area, and occurs relatively less at the non-coated end.

[0076] Referring again to FIG. 5, in the rolling step (S2), the foil (10) coated with the active material layer (11) by the slot die (2) is rolled and flattened in the thickness direction while passing through the rolling roller (3).

[0077] The rolling roller (3) according to the present embodiment may be configured as a pair of rollers spaced apart in the thickness direction so as to contact both surfaces of the foil (10) so as to press the foil (10) and the active material layer (11) in the thickness direction. However, as long as it can perform rolling and flattening operations, it may have another form, such as a press that moves up and down, regardless of its name.

[0078] Fig. 7 illustrates a cross-section of an overlap portion according to one embodiment. Referring again to Fig. 5, in the coating step (S1) according to one embodiment, an overlap portion (111) may be formed in which the active material layer (11) is double-coated or more over at least a portion of the area extending in the width direction on both sides of the foil (10).

[0079] Specifically, the overlapping portion (111) can be formed by overlapping the first coating area (11a) of the slot die (2) and the second coating area (11b) immediately thereafter by a predetermined length.

[0080] Figures 8 and 9 illustrate how the overlap portion is flattened in a rolling step according to one embodiment. As shown in these drawings, the overlap portion (111) is formed thicker than the remaining portion of the active material layer (11) and can be flattened in the rolling step (S2). Accordingly, the active material layer (11) can be continuously flattened along the longitudinal direction without any uneven rolling due to sliding.

[0081] Fig. 10 illustrates a coating step according to another embodiment. Referring to this, an extension (200) having a larger width than the remaining portion may be formed at both longitudinal ends of the discharge slit (20) according to another embodiment.

[0082] The electrode manufacturing method according to the above-described other embodiment can be performed using a slot die (2) having an expansion portion (200) as described above. Specifically, the expansion portion (200) has a larger width and forms a larger discharge cross-sectional area per unit length, so that the active material slurry can be discharged at a larger flow rate even under the same pressure as the remaining portion. Accordingly, the thickness of the active material layer (11) in the portion corresponding to the expansion portion (200) becomes relatively large, and a raised portion (112) having a thicker thickness than the remaining portion can be formed in the portion corresponding to the longitudinal end of the discharge slit (20) in the active material layer (11).

[0083] Fig. 11 shows a cross-section of a raised portion according to another embodiment, and Figs. 12 and 13 show how the raised portion is flattened in the rolling step according to another embodiment. Referring to these drawings, the raised portion (112) can be formed at a portion corresponding to the longitudinal end of the discharge slit (20) of the slot die (2). Accordingly, even if sliding occurs in the portion corresponding to the longitudinal end of the discharge slit (20) in the active material layer (11), the thickness thereof can be formed thicker than that of the remaining portion of the active material layer (11). The raised portion (112) formed so thickly can be flattened in the rolling step (S2). Accordingly, the active material layer (11) can be continuously and flatly formed along the longitudinal direction without an uneven phenomenon of rolling due to sliding.

[0084] Specifically, the raised portion (112) may be formed at one longitudinal end of the first coating region (11a) and at the other longitudinal end adjacent to the one longitudinal end in the second coating region (11b) coated immediately after the first coating region (11a). At this time, through the rolling step (S2), a pair of raised portions (112) formed at the one longitudinal end and the other longitudinal end may be combined with each other to evenly fill the space between the first coating region (11a) and the second coating region (11b).

[0085] Figure 14 illustrates a slitting step according to one embodiment. Referring to this, the foil (10) after undergoing the rolling step (S2) undergoes a slitting step (S3) in which it is cut along the width direction at predetermined length intervals. As the slitting step (S3) is performed, the foil (10) is divided into a plurality of electrodes.

[0086] According to one embodiment, in the slitting step (S3), the foil (10) can be cut along a cutting line (4) extending in the width direction at intervals of a first length (L1).

[0087] At this time, it is preferable that the discharge slit (20) of the slot die (2) is extended by a second length (L2) that is greater than the first length (L1). If the second length (L2) is shorter than the first length (L1), a sliding portion may be located between a pair of adjacent cutting lines (4), and thus this can be prevented by making the second length (L2) greater than the first length (L1).

[0088] Specifically, it is preferable that the second length (L2) be at least twice the first length (L1). In this case, two or more electrodes (1) that do not include a sliding portion can be obtained from an area once coated by the slot die (2).

[0089] According to one embodiment, in the slitting step (S3), the cutting line (4) is preferably located at a portion where the active material layer (11) is continuously coated on both sides in the longitudinal direction. In this case, the longitudinal ends of the electrode (1) can be formed flat without a sliding phenomenon, thereby improving the adhesion to the separator, stabilizing the charge / discharge performance, and preventing short circuits.

[0090] The above electrode may be an anode or a cathode. When the electrodes are laminated to form an electrode assembly, the anode and the cathode may be alternately and repeatedly laminated with a separator interposed between them. The electrode without an insulating layer coating and the electrode with an insulating layer coating, which will be described below, may correspond to one of the anode and cathode that is relatively less susceptible to short circuits and the other that is relatively susceptible to short circuits, respectively.

[0091] Fig. 15 illustrates an electrode without an insulating layer coating according to one embodiment. Referring to this, the electrode (1) may not be coated with a separate insulating layer. In this case, the electrode (1) includes the active material layer (11) and the non-coated portion (12) on which the active material layer (11) is not coated.

[0092] Figures 16 and 17 respectively show the appearance of the electrode of Figure 15 before and after undergoing a rolling step in a foil state. Referring to these drawings, in the coating step (S1) according to one embodiment, a raised portion (113) may be formed on at least one of the widthwise opposite ends of the active material layer (11), in which the active material layer (11) is coated more thickly along the lengthwise direction than the remaining portion. The raised portion (113) may be formed by additionally discharging the active material slurry while the slot die (2) is temporarily stopped before and / or after starting and / or finishing relative movement in the widthwise direction with respect to the foil (10).

[0093] For example, when the slot die (2) starts coating from the non-coated portion side, the slot die (2) may form the raised portion (113) by discharging the active material slurry for a predetermined period of time in a stationary state and then start relative movement to perform coating on the remaining portion. Alternatively, the slot die (2) may form the raised portion (113) by discharging the active material slurry while moving relative to the widthwise end of the foil (10) and coating the active material layer (11), and then reaching the boundary of the non-coated portion side of the active material layer (11) and discharging the active material slurry in a momentary stop state.

[0094] The above-mentioned raised portion (113) is preferably formed along the end of the non-coated portion (12) of the active material layer (11). Accordingly, even if sliding occurs at the end of the non-coated portion of the active material layer (11), the thickness thereof can be formed thicker than that of the remaining portion of the active material layer (11). The raised portion (113) formed so thickly can be flattened in the rolling step (S2), and accordingly, the adhesive strength between the electrode and the separator, the stability of charge / discharge performance, and the safety against short circuits can be improved.

[0095] Fig. 18 illustrates an electrode coated with an insulating layer according to one embodiment. Referring to this, the electrode (1) may include an insulating layer (13) coated along the boundary between the active material layer (11) and the non-conductive portion (12).

[0096] The above insulating layer (13) may include a cover portion (131) covering the active material layer (11) and an attachment portion (130) attached to the non-conductive portion (12).

[0097] By providing the insulating layer (13), the active material layer (11) is prevented from being exposed through the space between the pair of separators interposing the electrode (1), and the risk of a short circuit can be reduced. Accordingly, the insulating layer (13) may be provided on the side more vulnerable to a short circuit among the positive and negative electrodes. However, it is also possible for the insulating layer (13) to be provided on both the positive and negative electrodes.

[0098] Figures 19 and 20 respectively show the appearance of the electrode of Figure 18 before and after going through the rolling step in a foil state. Referring to these drawings,

[0099] According to one embodiment, the cover portion (131) may include an arch portion (132) having an arch shape convex toward the non-coated portion. The arch portion (132) may be formed by rolling the electrode (1) while the raised portion (113) is formed at the end of the non-coated portion of the active material layer (11) and the cover portion (131) covers the raised portion (113). More specifically, while the inner end of the attachment portion (130) is firmly attached to the foil (10), the raised portion (113) is rolled and protrudes in a horizontal direction, so that the cover portion (131) also forms the arch portion (132) protruding toward the non-coated portion.

[0100] According to one embodiment, an electrode structure is provided in which an end portion of an active material layer is formed flat, thereby preventing insufficient attachment of an electrode and a separator due to sliding, a risk of short circuit, and instability of charge / discharge performance due to unevenness of the active material layer.

[0101] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be determined by the claims that follow, rather than by the detailed description set forth above. Furthermore, the meaning and scope of the claims that follow, as well as all possible modifications and variations derived from their equivalent concepts, should be construed as encompassing the scope of the present invention.

[0102] Although the present invention has been described with reference to the drawings exemplified above, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical idea of ​​the present invention. Furthermore, even if the operational effects according to the configuration of the present invention have not been explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be acknowledged.

Claims

1. A coating step is included, in which an active material slurry is applied to both sides of a foil that is rolled and rolled from a foil roll having a predetermined first width to coat an active material layer, wherein the active material layer is coated on a portion excluding a non-coated portion extending along one end of the width direction of the foil to a predetermined second width. A method for manufacturing an electrode, wherein in the above coating step, the coating of the active material layer is performed by a slot die that moves relative to the foil in the width direction and discharges the active material slurry.

2. A method for manufacturing an electrode according to claim 1, wherein the active material slurry is discharged when the slot die moves relative to the first width direction and is not discharged when the slot die moves relative to the second width direction.

3. A method for manufacturing an electrode according to claim 1, wherein the active material slurry is discharged when the slot die moves in the first width direction and the second width direction.

4. In claim 1, the electrode manufacturing method further includes, after the coating step, a slitting step of cutting the foil along a cutting line extending in the width direction at a first length interval to form an electrode. A method for manufacturing an electrode, wherein the discharge slit of the above slot die is extended by a second length that is greater than the first length.

5. A method for manufacturing an electrode according to claim 4, wherein the second length is at least twice the first length.

6. A method for manufacturing an electrode according to claim 4, wherein, in the slitting step, the cutting line is located at a portion where the active material layer is continuously coated on both sides in the longitudinal direction.

7. In claim 1, the electrode manufacturing method further comprises, after the coating step, a rolling step of flattening the foil by rolling it in the thickness direction.

8. A method for manufacturing an electrode according to claim 7, wherein, in the coating step, an overlapping portion is formed in which the active material layer is double-coated or more in at least some areas extending in the width direction on both sides of the foil.

9. A method for manufacturing an electrode according to claim 8, wherein the overlapping portion is formed by overlapping the first coating area of ​​the slot die and the second coating area immediately thereafter by a predetermined length.

10. A method for manufacturing an electrode according to claim 7, wherein, in the coating step, a raised portion is formed in which the active material layer is coated thicker than the remaining portion in at least some areas extending in the width direction on both sides of the foil.

11. A method for manufacturing an electrode according to claim 10, wherein the raised portion is formed at a portion corresponding to a longitudinal end of the discharge slit of the slot die.

12. A method for manufacturing an electrode according to claim 7, wherein, in the coating step, a raised portion is formed on at least one of the widthwise ends of the active material layer, in which the active material layer is coated more thickly along the lengthwise direction than the remaining portion.

13. A method for manufacturing an electrode according to claim 12, wherein the raised portion is formed along the non-conductive portion side end of the active material layer.

14. A slot die that coats an active material layer by applying an active material slurry on both sides of a foil that is rolled out from a foil roll with a predetermined width and runs. The above active material slurry is discharged and includes a discharge slit extending in the longitudinal direction, A slot die configured to move relative to the foil in the width direction and discharge the active material slurry.

15. A slot die according to claim 14, wherein an extension portion having a larger width than the remaining portion is formed at both longitudinal ends of the discharge slit.

16. Foil; An active material layer coated on both sides of the above foil; A non-coated portion extending in the longitudinal direction along one end of the width direction of the above foil and not coated with the active material layer; and It includes an insulating layer including a cover part covering the active material layer and an attachment part attached to the non-conductive part, An electrode, wherein the above cover portion includes an arch portion having a convex arch shape toward the non-conductive portion.

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