Title of the invention: Coating die including double slits and electrode active material coating device using the same Technical field [One] The present invention relates to a coating die including double slits and an electrode active material coating apparatus using the same. [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0115337 filed on September 19, 2019, and all contents disclosed in the documents of the Korean patent application are included as part of this specification. Background [3] As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and the use of secondary batteries as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs) has recently been realized. Has become. Accordingly, many studies are being conducted on secondary batteries that can meet various needs, and in particular, there is a high demand for lithium secondary batteries having high energy density, high discharge voltage, and output stability. [4] In particular, lithium secondary batteries used in electric vehicles must be used for more than 10 years under severe conditions in which charging and discharging by a large current is repeated in a short time, along with the characteristics that can exhibit high energy density and large output in a short time. It is inevitably required to have superior safety and long life characteristics compared to small lithium secondary batteries. [5] In particular, the electrode of a lithium secondary battery is an important factor determining the long-term life as well as the initial characteristics of the battery, and has been studied from various angles from the active material to the manufacturing process. In order to improve the performance of a secondary battery, the development of an electrode structure in which active material layers having a two-layer structure are formed on a current collector is drawing attention. [6] However, an electrode active material coating apparatus for forming an active material layer having a two-layer structure includes a first slit nozzle and a second slit nozzle for forming active material layers having a two-layer structure on a current collector. In the conventional electrode active material coating apparatus, there is a problem in that the height of the first slit nozzle and the second slit nozzle cannot be controlled, or the gap between the first slit and the second slit occurs due to the weight of a connection pipe. Detailed description of the invention Technical challenge [7] The present invention was invented to solve the above problems, and a coating die including a double slit capable of effectively controlling the parameters of the coating process and compensating for the gap between the blocks, and an electrode active material coating apparatus including the same It aims to provide. Means of solving the task [8] The coating die including a double slit according to the present invention comprises: first to fourth blocks sequentially adjacent and positioned; A first slit formed at an interface between the first and second blocks to discharge a first coating liquid; A second slit formed at an interface between the third and fourth blocks to discharge a second coating solution; And a position control unit for controlling a position by moving the first and second blocks in a direction perpendicular to the ground. [9] The position control unit includes a support plate supporting lower portions of the first and second blocks, and a driving unit that contacts the lower portion of the support plate, and changes the position of the support plate in a direction perpendicular to the ground as it moves in a direction parallel to the ground. The coating die comprising a double slit, characterized in that the interface in contact with the lower portion of the support plate and the driving unit forms an angle of 5 to 30° with respect to the moving direction of the driving unit. [10] In one example, the interface in contact with the lower portion of the support plate and the driving unit may more preferably form an angle of 10 to 20°. [11] More specifically, the position control unit may further include a moving shaft formed along a moving path of the driving unit and supporting through the driving unit, and a hand lever connected to the moving shaft to control the movement of the moving shaft. [12] In this case, the moving shaft and the driving part through which the moving shaft passes are each formed with threads to engage with each other, and by operating the hand lever, the driving part can be moved along the length direction of the moving shaft while the moving shaft rotates. [13] [14] One or two or more spherical or cylindrical bearings are provided at an interface where the lower portion of the support plate and the driving unit are in contact, thereby reducing friction at the interface. [15] [16] [17] In another embodiment of the present invention, the coating die comprising the double slits, [18] It may further include an auxiliary position control unit for moving the first and second blocks in a downward direction perpendicular to the ground. [19] At this time, the auxiliary position control unit is located above the first block, and as it descends in a direction perpendicular to the ground, it contacts the outer surface of the first block and presses it to move the first and second blocks. By manufacturing in a shape corresponding to the shape of the outer surface of the block, it can serve to assist in preventing the first slit and the second slit from spreading. [20] [21] In one example, the coating die according to the present invention includes a first coating liquid storage unit formed between the first and second blocks to supply a first coating liquid to the first slit, and the first coating liquid storage unit is a first block It is a structure that is fluidly connected to the coating liquid injection channel passing through it. [22] In one example, the coating die according to the present invention includes a second coating liquid storage unit formed between the third and fourth blocks to supply a second coating liquid to the second slit, and the second coating liquid storage unit is a fourth block It is a structure that is fluidly connected to the coating liquid injection channel passing through it. [23] In one example, the interface between the second and third blocks is perpendicular to the ground, but the second and third blocks have a shape in which the width of the cross section gradually decreases in the upward direction. In a specific example, the discharge direction in which the first and second coating liquids are discharged through the first and second slits is directed upward, but is a direction converging toward an extension line of an interface where the second and third blocks are in contact. In addition, in response to changes in the positions of the first and second blocks by the position control unit, the step difference between the first and second slits is changed. [24] In one example, it further includes a micro gauge indicating a change in the position of the first and second blocks by the position control unit. [25] In addition, the present invention provides an electrode active material coating apparatus including the coating die described above. [26] In one example, the coating die has a structure in which an electrode active material is discharged on one surface of an electrode current collector through first and second slits, and a double layer of the electrode active material is formed. [27] In a specific example, in the coating die, each of the first and second slits discharges the electrode active material upward, and discharges the electrode active material to the lower surface of the electrode current collector through the second slit to form a lower active material layer. An upper active material layer is sequentially formed on the lower active material layer through one slit. Effects of the Invention [28] The coating die including a double slit and an electrode active material coating apparatus using the same according to the present invention have an effect of preventing a phenomenon in which a slip surface between blocks constituting a die is spreading, and reducing an offset of a coating process. Brief description of the drawing [29] 1 is a cross-sectional view of an electrode active material coating apparatus according to an embodiment of the present invention. [30] 2 is a perspective view of an electrode active material coating apparatus according to an embodiment of the present invention. [31] 3 is a front view of an electrode active material coating apparatus according to an embodiment of the present invention. [32] 4 is a perspective view of an electrode active material coating apparatus according to still another embodiment of the present invention. Mode for carrying out the invention [33] Hereinafter, the present invention will be described in detail. Prior to this, terms or words used in the present specification and claims are not limited to their usual or dictionary meanings and should not be construed, and the inventors appropriate the concept of terms in order to describe their own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of ​​the present invention on the basis of the principle that it can be defined. [34] In the present invention, "coating liquid" is a generic term for a component that is discharged onto a substrate to form a coating layer, and includes, for example, a slurry state. [35] [36] The present invention relates to a double slit coating die, comprising: first to fourth blocks sequentially adjacent and positioned; A first slit formed at an interface between the first and second blocks to discharge a first coating liquid; A second slit formed at an interface between the third and fourth blocks to discharge a second coating solution; And a position control unit for controlling a position by moving the first and second blocks in a direction perpendicular to the ground. [37] In one example, the position control unit is in contact with a support plate supporting lower portions of the first and second blocks and a lower portion of the support plate, but changes the position of the support plate in a direction perpendicular to the ground as it moves in a direction parallel to the ground. And a driving unit, wherein the interface between the lower portion of the support plate and the driving unit forms an inclination with an angle exceeding 0 with respect to the moving direction of the driving unit. The angle is in the range of 5 to 30°, specifically in the range of 10 to 20° or in the range of 10 to 15°. [38] [39] The double slit coating die according to the present invention has a structure including four blocks, a first slit is formed at the interface of the first and second blocks, and a second slit is formed at the interface of the third and fourth blocks. . Each of the first and second slits discharges the first and second coating solutions to form a double-layered coating layer on the substrate. For example, the second coating liquid discharged through the second slit forms a lower coating layer on the substrate, and the first coating liquid discharged through the first slit forms an upper coating layer on the lower coating layer. In order to sequentially form the lower and upper coating layers on the substrate, it is necessary to adjust the separation distance or step difference between the first and second slits. To this end, the positions of the first slit are adjusted by controlling the positions of the first and second blocks. In order to adjust the position of the first slit, it is necessary to form a structure in which the second and third blocks are separated into two blocks. However, when the second and third blocks form separate blocks that operate separately, the interface between the second and third blocks is widened due to the weight of the injection pipe connected to the coating die. For example, if the gap between the second and third blocks is widened, the gap between the first and second slits also increases, which acts as a process variable of the double-slot coating die according to the present invention. [40] [41] In the present invention, when controlling the vertical position of the first and second blocks, as the driving unit in contact with the lower portion of the support plate moves in a direction parallel to the ground, the support plate moves along an inclined interface between the driving unit and the support plate. Therefore, the force applied to the first and second blocks acts not only in the direction perpendicular to the ground, but also in the direction inside the die, that is, in the direction where the interface between the second block and the third block is. The losing force becomes the result of these two forces. At this time, the force acting inside the die can be adjusted according to the angle of the interface between the lower part of the support plate and the driving part, and as a result of an experiment by the applicant of the present invention, the phenomenon that the interface should not be widened is not observed when it is at least 5°. Accordingly, it is possible to compensate for the gap between the second and third blocks and to effectively control the parameters of the coating process. In addition, a detachment preventing member is formed at one end of the support plate to support while contacting the side surface of the first block, thereby preventing the first block from being pushed in the lateral direction and disengaging. [42] The angle can be adjusted according to the type, location, weight, etc. of the device additionally mounted on the slot die, but if it exceeds 30°, the force applied to the inside of the slot die is excessively large, so the second block and the third block The friction force at the interface of the block may become too great, making it difficult to control the position. [43] In one embodiment, the position control unit includes: a moving shaft formed along a moving path of the driving unit and supporting through the driving unit; And a hand lever connected to the moving shaft to control the movement of the moving shaft, and a screw thread may be formed inside the moving shaft and the driving part through which the moving shaft passes so as to engage with each other. In this case, when the moving shaft is rotated by manipulating the hand lever, it is possible to move the driving part in one direction along the moving shaft while rotating the screw threads engaged with each other. The operation of the hand lever is performed either directly by the operator or by instructions from a programmed computer. [44] On the other hand, while the driving unit moves along the moving axis, the support plate is raised or lowered by applying a force to the support plate along the interface in contact with the support plate. At this time, one or two or more spherical or cylindrical bearings may be provided at the interface between the driving part and the support plate in order to reduce the frictional force of the interface and facilitate movement. [45] [46] In addition, as another embodiment of the present invention, it may further include an auxiliary position control unit for moving the first and second blocks in a downward direction perpendicular to the ground. The position control unit of the present invention serves to control the vertical position of the first and second blocks by raising or lowering the support plate, but when the support plate is lowered, only the force acting on the first and second blocks is gravity. Therefore, when the interfacial frictional force between the second block and the third block, which is the slip surface, increases according to the process variable, the descending is not smooth only by gravity, and thus position control failure may occur. [47] The auxiliary position control unit may contact the outer surface of the first block and apply an additional force other than gravity from the upper to the lower direction while descending, thereby solving a problem of a lower position control failure that may occur due to the frictional force of the slip surface. In addition, like the separation preventing member of the support plate, there is also an auxiliary effect of preventing the spreading by supporting the upper part of the first block so as not to be separated from the side. [48] [49] In one embodiment, a first coating liquid storage part formed between the first and second blocks and supplying a first coating liquid to the first slit, and the first coating liquid storage part includes a coating liquid injection passage passing through the first block and It is a fluid-connected structure. In addition, it is formed between the third and fourth blocks, and includes a second coating solution storage unit for supplying a second coating solution to the second slit, and the second coating solution storage unit has a structure fluidly connected to a coating solution injection passage passing through the fourth block. . [50] [51] [52] In one example, a double slit coating die according to the present invention consists of four blocks. The interface between the first and second blocks forms a first slit, and the interface between the third and fourth blocks forms a second slit. The first and second blocks have a structure in which height can be adjusted by a position control unit. In this case, the first and fourth blocks are positioned outside the double slit coating die, respectively, and the coating liquid is supplied through the first and fourth blocks, respectively. An injection pipe or the like for supplying a coating solution is connected to the first and fourth blocks, respectively, and an air vent facility or the like is connected as necessary. These connecting pipes are not only heavy in weight, but also regularly or irregularly apply force to the coating die side by a fastened supply pump or air compressor. In the double slit coating die according to the present invention, a phenomenon in which the interface between the second and third blocks is widened due to the weight of the inlet pipe or the like may occur. In the present invention, by controlling the positional movement direction of the first and second blocks, it is possible to compensate for the gap between the second and third blocks and to effectively control the parameters of the coating process. [53] For example, in the double slit coating die according to the present invention, the interface between the second and third blocks is perpendicular to the ground, but the second and third blocks have a form in which the width of the cross section gradually decreases in the upward direction. . In this case, the double slit coating die according to the present invention is a vertical coating die, and the discharging direction of the coating liquid is the upper direction. When the substrate layer is moved by a conveyor above the double slit coating die, coating is performed on the lower surface of the substrate layer. Specifically, the discharge direction in which the first and second coating liquids are discharged through the first and second slits is directed upward, but is a direction converging toward an extension line of an interface where the second and third blocks are in contact. A lower coating layer and an upper coating layer are formed on the base layer by forming such that the discharge directions for discharging the first and second coating solutions through the first and second slits converge toward an extension line of the interface where the second and third blocks are in contact. Is formed continuously. [54] In another embodiment, in response to changes in the positions of the first and second blocks by the position control unit, the step difference between the first and second slits is changed. When the positions of the first and second blocks are changed by the position control unit, the positions of the first slit for discharging the first coating liquid are also changed accordingly. For example, when the positions of the first and second blocks move in a vertical upward direction, the positions of the first slit also move upward. In addition, in the present invention, the "step difference between the first and second slits" means a phase difference between the discharge port of the first slit and the discharge port of the second slit. For example, when the double slit coating die according to the present invention is a vertical coating die, the step difference between the first and second slits represents a height difference between the discharge port of the first slit and the discharge port of the second slit. By controlling the step difference between the first and second slits, the thickness of the lower and upper coating layers and/or the thickness ratio of each layer are controlled. [55] For example, it may further include a microgauge indicating the position change of the first and second blocks by the position control unit. Changes in the positions of the first and second blocks are checked through the microgauge. The microgauge may indicate the positions of the first and second blocks, or may indicate the degree of control of the position control unit as a level difference between the first and second slits. Alternatively, when the support plates supporting the first and second blocks are moved by the operation of the hand lever, the microgauge may display the operating level of the hand lever. [56] [57] In addition, the present invention provides an electrode active material coating apparatus including the double slit coating die described above. [58] In one embodiment, the double slit coating die has a structure in which an electrode active material is discharged on one surface of an electrode current collector through first and second slits, and a double layer of the electrode active material is formed. [59] Specifically, in the double slit coating die, each of the first and second slits discharges an electrode active material upward. For example, the electrode active material is discharged to the lower surface of the electrode current collector through the second slit to form the lower active material layer, and the upper active material layer is sequentially formed on the lower active material layer through the first slit. [60] The electrode active material is a secondary battery, specifically, an electrode active material of a lithium secondary battery. The electrode active material coating apparatus according to the present invention is an apparatus for coating an electrode active material on a current collector, and through this, an electrode coated with an active material having a two-layer structure is manufactured. [61] In one example, the electrode means a positive electrode and/or a negative electrode of a lithium secondary battery. [62] The positive electrode has a structure in which a positive electrode active material layer of a two-layer structure is stacked on a positive electrode current collector. In one example, the positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder polymer, and if necessary, may further include a positive electrode additive commonly used in the art. [63] The positive electrode active material may be a lithium-containing oxide, and may be the same or different. As the lithium-containing oxide, a lithium-containing transition metal oxide may be used. [64] For example, the lithium-containing transition metal oxide is Li x CoO 2 (0.5 [89] 110: first block [90] 111: first coating liquid injection port [91] 112: first coating liquid storage unit [92] 113: first coating liquid injection flow path [93] 120: second block [94] 130: third block [95] 140: fourth block [96] 141: second coating liquid injection port [97] 142: second coating liquid storage unit [98] 143: second coating liquid injection flow path [99] 201, 202, 203, 204: air vent [100] 301, 302: hand lever [101] 310: support plate [102] 311: separation preventing member [103] 320: drive unit [104] 330: moving axis [105] 410, 420: micro gauge [106] 510: auxiliary position control unit Claims [Claim 1] First to fourth blocks sequentially adjacent and positioned; A first slit formed at an interface between the first and second blocks to discharge a first coating liquid; A second slit formed at an interface between the third and fourth blocks to discharge a second coating solution; And a double slit including a position control unit for controlling a position by moving the first and second blocks in a direction perpendicular to the ground. [Claim 2] The apparatus of claim 1, wherein the position control unit comprises: a support plate supporting lower portions of the first and second blocks; And a driving unit that contacts a lower portion of the support plate, but changes a position of the support plate in a direction perpendicular to the ground as it moves in a direction parallel to the ground, and an interface between the lower portion of the support plate and the driving unit is in a moving direction of the driving unit. Coating die comprising a double slit, characterized in that forming an angle of 5 to 30 degrees with respect to. [Claim 3] The apparatus of claim 2, wherein the position control unit comprises: a moving shaft formed along a moving path of the driving unit and supporting through the driving unit; And a hand lever connected to the moving shaft to control the movement of the moving shaft. [Claim 4] 4. Coating die comprising a double slit, characterized in that to. [Claim 5] The coating die of claim 2, wherein one or more spherical or cylindrical bearings are provided at an interface where the lower portion of the support plate and the driving unit are in contact with each other. [Claim 6] The coating die of claim 1, wherein the coating die including the double slits further includes an auxiliary position control unit for moving the first and second blocks in a downward direction perpendicular to the ground. [Claim 7] The method of claim 6, wherein the auxiliary position control unit is located above the first block, and moves the first and second blocks by contacting and pressing the outer surface of the first block as it descends in a direction perpendicular to the ground. Coating die comprising a double slit, characterized in that. [Claim 8] The method of claim 1, wherein the first coating liquid storage part is formed between the first and second blocks to supply the first coating liquid to the first slit, and the first coating liquid storage part comprises a coating liquid injection passage passing through the first block and Coating die comprising double slits, characterized in that the fluid connected structure. [Claim 9] The method of claim 1, wherein the second coating liquid storage part is formed between the third and fourth blocks to supply a second coating liquid to the second slit, and the second coating liquid storage part comprises a coating liquid injection passage passing through the fourth block and Coating die comprising double slits, characterized in that the fluid connected structure. [Claim 10] The double slit according to claim 1, wherein the interface between the second and third blocks is perpendicular to the ground, and the second and third blocks have a form in which the width of the cross section gradually decreases in the upward direction. Including coating die. [Claim 11] The method of claim 10, wherein the discharge direction in which the first and second coating liquids are discharged through the first and second slits is directed upward, but is a direction converging toward an extension line of an interface where the second and third blocks are in contact. Coating die comprising a double slit, characterized in that. [Claim 12] The coating die of claim 1, wherein a step difference between the first and second slits is changed in response to a change in the position of the first and second blocks by the position control unit. [Claim 13] The coating die of claim 1, further comprising a micro gauge indicating a change in the position of the first and second blocks by the position control unit. [Claim 14] An electrode active material coating apparatus comprising the coating die according to claim 1. [Claim 15] 15. The electrode active material coating apparatus of claim 14, wherein the coating die has a structure in which an electrode active material is formed by discharging an electrode active material on one surface of the electrode current collector through first and second slits, respectively.