Negative electrode manufacturing system and negative electrode manufacturing method using same

Abstract

The present invention relates to a negative electrode manufacturing system and a negative electrode manufacturing method using same. The negative electrode manufacturing system includes a double slot die including an upper block body and a lower block die lip that exhibit different magnetic polarities, thereby enabling direct discharge of a negative electrode slurry to which a magnetic field is applied onto a moving current collector. In addition, the negative electrode slurry discharged from the dual slot die is applied such that plane-direction crystal planes of a carbon-based negative electrode active material are oriented at a predetermined angle with respect to the surface of the current collector onto which the negative electrode slurry is being applied, thereby significantly improving the orientation of the carbon-based negative electrode active material after rolling.

Description

Cathode manufacturing system and cathode manufacturing method using the same

[0001] The present invention relates to a system for manufacturing a cathode and a method for manufacturing a cathode using the same.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0187335 dated December 16, 2024, and all contents disclosed in the document of said patent application are incorporated herein as part of this specification.

[0003]

[0004] Recently, rechargeable batteries are being widely applied not only to small devices such as portable electronic devices but also to medium-to-large devices such as battery packs for hybrid or electric vehicles or power storage systems. A rechargeable battery is a chargeable energy storage device composed of a stacked structure of a positive electrode, a separator, and a negative electrode. Generally, the positive electrode contains a lithium metal oxide as the positive electrode active material, and the negative electrode contains a carbon-based negative electrode active material such as graphite. Rechargeable batteries containing these components have a configuration in which lithium ions released from the positive electrode during charging are absorbed into the carbon-based negative electrode active material, and lithium ions contained within the carbon-based negative electrode active material are absorbed into the lithium metal oxide of the positive electrode during discharging, thereby enabling repeated charging and discharging.

[0005] Graphite materials such as natural graphite and artificial graphite can be used as the cathode active material for the above-mentioned cathode. Such graphite has a layered structure and is formed by stacking multiple layers in which carbon atoms form a network structure and are spread out in a planar shape. During charging, lithium ions penetrate from the edge surface (the surface where the layers overlap) of these graphite layers and diffuse between the layers, and during discharging, lithium ions can be released from the edge surface of the layers. Therefore, since the electrical resistivity in the plane direction of the layers of the graphite is lower than that in the stacking direction of the layers, a conduction path for electrons that bypasses along the plane direction of the layers is formed.

[0006] In this regard, a technique has been proposed to align the graphite contained in the negative electrode in a magnetic field to improve the charging performance of the negative electrode in a conventional lithium secondary battery using graphite. Specifically, during the formation of the negative electrode, the (002) crystal plane of the graphite is oriented in a magnetic field so that it is nearly perpendicular to the negative electrode current collector, and the configuration is fixed. In this case, since the edge plane of the graphite layer faces the positive active layer, the transport path of lithium ions is shortened, thereby improving the charging performance of the battery.

[0007] Such graphite orientation can be induced by applying a graphite-containing cathode slurry onto a cathode current collector and applying a magnetic field to the undried cathode slurry. However, considering the production speed during the mass production of actual cathodes, there is a problem in that it is difficult to secure sufficient time for applying a magnetic field to induce graphite alignment in the cathode slurry. Furthermore, even if this is resolved, there is a limitation in that the effect of improving the charging performance of the secondary battery is minimal because the degree of graphite orientation is reduced when rolling is performed to increase the energy density of the cathode.

[0008]

[0009] [Prior Art Literature]

[0010] [Patent Literature]

[0011] Japanese Patent Publication No. 2023-083791

[0012]

[0013] The objective of the present invention is to provide a cathode manufacturing technology that exhibits high productivity during cathode manufacturing and has excellent graphite orientation of the finally manufactured cathode after rolling.

[0014]

[0015] In order to solve the aforementioned problem,

[0016] The present invention is,

[0017] A transport unit that moves the entire house, and

[0018] It includes a dual slot die comprising an upper block, an intermediate block, and a lower block, a first slot provided through the gap between the upper block and the intermediate block for discharging a first cathode slurry, and a second slot provided through the gap between the intermediate block and the lower block for discharging a second cathode slurry;

[0019] When the upper block, middle block, and lower block are divided into a die lip forming a discharge port at each tip and a body extending from the die lip, the body of the upper block and the die lip of the lower block provide a cathode manufacturing system that exhibits magnetism of different polarities.

[0020] The body of the upper block and the die lip of the lower block may each include one or more types of magnets among permanent magnets and electromagnets.

[0021] At this time, the distance between the magnet included in the body of the upper block and the magnet included in the die lip of the lower block can be adjusted.

[0022] The body of the upper block and the die rib of the lower block may each have a magnetic flux density in the range of 0.05 T to 1.0 T.

[0023] The above double slot die can be arranged so that the second slot and the first slot are located from upstream to downstream along the direction of movement of the current collector.

[0024] The first slot and the second slot can each be arranged to have an angle ranging from 50° to 130° relative to the surface of the current collector coated with the cathode slurry.

[0025] The above double slot die is configured to be tiltable so as to be able to adjust the angle formed by the first slot and the second slot with the surface of the current collector.

[0026] The above cathode manufacturing system may further include a drying unit for drying a first cathode slurry and a second cathode slurry applied on a current collector by the double slot die, and a rolling unit for pressing the surface of the first cathode slurry dried by the drying unit.

[0027] The above rolling section can apply pressure in a vertical direction relative to the surface of the dried first cathode slurry.

[0028]

[0029] Furthermore, the present invention,

[0030] A method for manufacturing a cathode is provided, comprising the step (S1) of sequentially applying a second cathode slurry and a first cathode slurry, to which a magnetic field is applied, onto a moving current collector using a cathode manufacturing system according to the present invention, wherein the first cathode slurry and the second cathode slurry each comprise a carbon-based cathode active material.

[0031] The above method for manufacturing the cathode may further include, after step (S1), a step (S2) of drying the second cathode slurry and the first cathode slurry coated on the current collector to form a second cathode active layer and a first cathode active layer, and a step (S3) of rolling the formed first cathode active layer and the second cathode active layer.

[0032] The first cathode active layer has an orientation degree (OI) before rolling that is greater than the orientation degree (OI) after rolling, and the orientation degree (OI) can be represented by the following Equation 1:

[0033] [Equation 1]

[0034] OI = I 004 / I 110

[0035] In Equation 1,

[0036] I 004 represents the area of ​​the peak indicating the (004) crystal plane during X-ray diffraction spectroscopy (XRD) measurement of the cathode active layer, and

[0037] I 110This represents the area of ​​the peak indicating the crystal plane (110) when X-ray diffraction spectroscopy (XRD) is measured for the cathode active layer.

[0038] The first cathode active layer may have an orientation degree (OI) in the range of 0.5 to 10 after rolling.

[0039] The above-mentioned entire house can move at a speed ranging from 5 m / min to 100 m / min.

[0040]

[0041] The cathode manufacturing system according to the present invention has excellent productivity because it directly discharges a cathode slurry with a magnetic field applied onto a moving current collector. In addition, the cathode slurry discharged from the double slot die has the advantage of achieving high orientation of the carbon-based cathode active material after rolling, as the planar crystal planes of the carbon-based cathode active material are oriented at an angle within a predetermined range relative to the surface of the current collector coated with the cathode slurry.

[0042]

[0043] FIG. 1 is a cross-sectional view schematically showing the double die coater structure of a cathode manufacturing system (1) according to the present invention.

[0044] FIG. 2 is a structural diagram showing a double slot die (10) provided in a cathode manufacturing system according to the present invention.

[0045] FIG. 3 is a conceptual diagram illustrating the principle of coating a current collector with the plane-direction crystal planes of each carbon-based cathode active material of the first cathode slurry and the second cathode slurry oriented by means of a double slot die (10) when manufacturing a cathode using a cathode manufacturing system (1) according to the present invention.

[0046] FIG. 4 is a conceptual diagram schematically illustrating the principle that when manufacturing a cathode using the cathode manufacturing system (1) according to the present invention, the plane direction crystal plane inclination of the carbon-based cathode active material on the surface of the current collector increases due to the rolling section.

[0047]

[0048] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described in detail in the detailed description.

[0049] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0050] Furthermore, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only being "immediately above" the other part but also having another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only being "immediately below" the other part but also having another part in between. Additionally, in the present application, being "placed on" may include being placed not only on the upper part but also on the lower part.

[0051] In this specification, "include as a main component" may mean including a defined component in an amount of 50 wt% or more (or 50 volume% or more), 60 wt% or more (or 60 volume% or more), 70 wt% or more (or 70 volume% or more), 80 wt% or more (or 80 volume% or more), 90 wt% or more (or 90 volume% or more), or 95 wt% or more (or 95 volume% or more) with respect to the total weight (or total volume). For example, "include carbon atoms as a main component" may mean including 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, or 95 wt% or more based on the total weight of the carbon-based compound. In some cases, it may mean that the entire carbon-based compound consists of carbon atoms and is included in an amount of 100 wt%.

[0052]

[0053] The present invention will be described in more detail below.

[0054]

[0055] Cathode manufacturing system

[0056] The present invention provides a cathode manufacturing system comprising: a transfer unit for moving a current collector; and a double slot die comprising an upper block, an intermediate block, and a lower block, and a first slot and a second slot for discharging a cathode slurry through the respective gaps between the upper block and the intermediate block and between the intermediate block and the lower block.

[0057]

[0058] The cathode manufacturing system according to the present invention is applied when manufacturing a cathode used in a secondary battery and has a configuration for manufacturing an electrode sheet by applying a cathode slurry containing a carbon-based cathode active material onto a current collector.

[0059] Specifically, FIG. 1 is a cross-sectional view schematically showing the configuration of a cathode manufacturing system (1) according to the present invention, and FIG. 2 is a structural diagram showing the structure of a double slot die (10) provided in the cathode manufacturing system (1).

[0060] Referring to FIGS. 1 and 2, a cathode manufacturing system (1) according to the present invention includes a transfer unit (20) for moving a current collector; and a double slot die (10) for applying a cathode slurry to the moving current collector.

[0061] The above-mentioned transfer unit (20) is positioned on one side of the collector and performs the function of moving the collector in a contact and / or non-contact state. To this end, the above-mentioned transfer unit (20) may include one or more of a roll-to-roll machine, a conveyor machine, a suction machine, and an air-floating machine. For example, the above-mentioned transfer unit (20) may include a roll-to-roll machine having a plurality of rollers (21a, 21b, 21c, etc.) arranged along the movement path of the collector.

[0062] The above double slot die (10) is provided with a first slot (151) and a second slot (152) so that two types of cathode slurries, identical or different, can be applied simultaneously in a double manner on a current collector. Specifically, as shown in FIG. 2, the first slot (151) can be formed between the upper block (110) and the middle block (120) facing each other, and the second slot (152) can be formed between the middle block (120) and the lower block (130) facing each other. For example, the double slot die (100) may sequentially interpose a first spacer (141) and a second spacer (142) between each of the upper block (110), middle block (120), and lower block (130) to form a passage, i.e., slots (151 and 152), through which the first cathode slurry and the second cathode slurry can fluidly move.

[0063] The upper and lower heights of the first slot and the second slot may be determined by the thickness of the first spacer (141) and / or the second spacer (142) that implement the gap between each block. The thickness of the first spacer (141) and / or the second spacer (142) may be controlled according to the application or capacity of the secondary battery. Specifically, the thickness of each spacer (141 and 142) may independently be in the range of 50㎛ to 2,000㎛, and specifically, 50㎛ to 1,500㎛; 500㎛ to 1,200㎛; 800㎛ to 1,200㎛; 300㎛ to 500㎛; 500㎛ to 1,000㎛; 80㎛ to 400㎛; 80㎛ to 200㎛; 200㎛ to 500㎛; 100㎛ to 300㎛; Or it may be in the range of 400㎛ to 700㎛.

[0064] The first spacer (141) and / or the second spacer (142) may have an opening (not shown) formed by cutting off a portion of one area, and may be interposed in the remaining portion excluding one side of the respective opposing edge areas of the upper block (110), middle block (120), and lower block (130). Accordingly, the discharge port through which the cathode slurry is discharged to the outside is formed only between the leading portions of the upper block (110), middle block (120), and lower block (130). Each leading portion of the upper block (110), middle block (120), and lower block (130) includes an upper die lip (111), a middle die lip (121), and a lower die lip (131), and the first slot (151) and second slot (152) through which the cathode slurry is discharged may be formed by the space between each die lip.

[0065] The first spacer (141) and the second spacer (142) can also function as gaskets to prevent cathodic slurry from leaking into the gaps between each block (110, 120, and 130), except for the area forming the first slot (151) and the second slot (152). Accordingly, it is preferable that the first spacer (141) and the second spacer (142) be made of a material having sealing properties.

[0066] Meanwhile, the upper block (110), middle block (120), and lower block (130) may include an upper body (112), a middle body (122, not shown), and a lower body (132) that extend from each die lip and form a passage through which the cathode slurry can fluidly move by being in close contact with a first spacer (141) and / or a second spacer (142), together with an upper die lip (111), a middle die lip (121, not shown), and a lower die lip (131) located at each tip.

[0067] At this time, the upper body (112) and the lower die lip (131) may exhibit magnetism having different polarities. Accordingly, a magnetic field may be formed in the space between the upper body (112) and the lower die lip (131).

[0068] Specifically, referring to FIG. 3, the carbon-based cathode active material (C-NE) of the cathode slurry moves through the first slot (151) and the second slot (152) formed by separating each block (110, 120, and 130). At this time, the carbon-based cathode active material (C-NE) of the cathode slurry moves in a state with a high degree of freedom in the non-magnetic section. However, if the body of the upper block (110) (i.e., the upper body (112)) and the die lip of the lower block (130) (i.e., the lower die lip (131)) have magnetism of different polarities, an attractive force acts between the body of the upper block (112) and the die lip (131) of the lower block where magnetism is implemented. In this case, a magnetic field line that is close to a straight line (corresponding to the 'dotted arrow' in FIG. 3) is strongly formed between the body of the upper block (112) and the die lip (131) of the lower block. When the above cathode slurry passes through the corresponding section, the carbon-based cathode active material (C-NE) contained in the cathode slurry can have its plane-direction crystal plane (e.g., a (110) plane or a (100) plane formed along the ab-axis plane of graphite) oriented along the magnetic field lines. Since the carbon-based cathode active material (C-NE) oriented in this way is applied onto the current collector in an oriented state, it can be oriented at a predetermined angle (θ3) with respect to the surface of the current collector (C) without applying a separate magnetic field after the application of the cathode slurry.

[0069] The body (112) of the upper block and the die lip (131) of the lower block may each include a magnet (113 and 133) in the corresponding portion to exhibit magnetism. Specifically, the body (112) of the upper block and the die lip (131) of the lower block may include one or more types of permanent magnets and electromagnets. The electromagnets may include both DC electromagnets and AC electromagnets. Additionally, the permanent magnets may include both magnets with ferromagnetic properties and magnets with soft magnetic properties, such as NdFeB-based magnets, SmCo-based magnets, Ferrite magnets, Alnico magnets, FeCrCo-based magnets, and Bond magnets (Nd-Fe-B-based, Sm-Fe-N-based, Sm-Co-based, Ferrite-based).

[0070] Since the above double slot die (10) applies a magnetic field before the cathode slurry (S) is applied to the current collector (C), a magnetic field of relatively weak strength can be applied compared to the case where the magnetic field is applied after the cathode slurry is applied to the current collector. Specifically, the body (112) of the upper block and the die lip (131) of the lower block may each have a magnetic flux density in the range of 0.05 T (Tesla, ≈500G (Gauss)) to 1.0 T (≈10,000G). For example, the body (112) of the upper block and the die lip (131) of the lower block may each have a magnetic flux density of 0.05 T to 0.9 T; 0.05 T to 0.8 T; 0.05 T to 0.7 T; 0.05 T to 0.6 T; 0.05 T to 0.5 T; 0.1 T to 0.9 T; It may have a magnetic flux density in the range of 0.2 T to 0.9 T; 0.3 T to 0.9 T; 0.4 T to 0.9 T; 0.5 T to 0.9 T; 0.6 T to 0.9 T; 0.2 T to 0.6 T; 0.3 T to 0.7 T; 0.4 T to 0.8 T; 0.05 T to 0.4 T; 0.05 T to 0.3 T; 0.1 T to 0.4 T; 0.05 T to 0.25 T; 0.05 T to 0.2 T; 0.05 T to 0.15 T; 0.1 T to 0.2 T; 0.2 T to 0.25 T; 0.05 T to 0.15 T; or 0.05 T to 0.09 T. The present invention allows for the uniform realization of the crystal plane orientation of a carbon-based cathode active material before the cathode slurry is discharged through the first slot (151) and the second slot (152) by adjusting the magnetic flux density of the body (112) of the upper block and the die lip (131) of the lower block to the above range, thereby enabling the coating on the current collector (C). Additionally, by preventing the separation distance between blocks constituting the double slot die (10) from narrowing by exceeding the above upper limit of the magnetic flux density of the body (112) of the upper block and the die lip (131) of the lower block, high productivity can be maintained during cathode manufacturing.

[0071] Meanwhile, the above double slot die (10) can have conditions such as the position of each slot, the position of the magnet included in the double slot die, the distance between the magnets, and the angle between the slot and the surface of the current collector adjusted so that the plane-direction crystal plane of the carbon-based negative electrode active material (C-NE) included in the negative electrode slurry (S) can be oriented at a predetermined angle (θ3) with respect to the surface of the current collector (C). Since the orientation angle of the carbon-based negative electrode active material (C-NE) applied may differ depending on the room temperature viscosity of the negative electrode slurry (S) applied on the current collector or the moving speed of the current collector, and the final orientation angle of the carbon-based negative electrode active material (C-NE) may differ depending on the pressure conditions during rolling of the dried negative electrode slurry, the above conditions can be appropriately controlled by comprehensively considering these parameters.

[0072] Specifically, the carbon-based negative electrode active material (C-NE) may be applied such that the crystal plane in the plane direction forms a predetermined angle (θ3) with respect to the surface of the current collector (C). The angle (θ3) may have an angle in the range of 45° to 135° with respect to the surface of the current collector (C) on which the negative electrode slurry is applied. For example, the angle (θ3) may be an acute angle in the range of less than 90° that is inclined downstream along the transport direction of the current collector with respect to the surface of the current collector (C) on which the negative electrode slurry is applied. Specifically, the acute angle may be an angle in the range of 45° to 89°; 45° to 60°; 50° to 70°; 55° to 80°; 65° to 70°; 55° to 70°; 60° to 75°; or 65° to 80°. Additionally, the angle (θ3) may be an obtuse angle exceeding 90° that is inclined upstream along the transport direction of the current collector with respect to the surface of the current collector (C) coated with the cathode slurry, and the obtuse angle may be an angle in the range of greater than 90° and less than or equal to 135°; 91° to 130°; 91° to 120°; 91° to 110°; 95° to 130°; 95° to 120°; 110° to 135°; 105° to 120°; or 100° to 115°. The angle (θ3) may be an angle considered so that the orientation angle of the carbon-based cathode active material (C-NE) can be oriented close to vertical after rolling the dried cathode slurry.

[0073] The above double slot die (10) is positioned on the upper part of a moving current collector (C), and can be arranged so that the second slot (152) and the first slot (151) are sequentially positioned from upstream to downstream along the direction of movement of the current collector. In this case, since the magnetic field lines induced between the body (112) of the upper block and the die lip (131) of the lower block have a similar value that is the same as or has a predetermined deviation from the orientation angle (θ3) of the coated carbon-based negative electrode active material (C-NE), there is an advantage in that the orientation angle of the carbon-based negative electrode active material (C-NE) can be easily controlled.

[0074] As described above, the double slot die (10) exhibits magnetism of different polarities in the body of the upper block and the die lip of the lower block, so that as the cathode slurry moves through each slot (151 and 152), the planar crystal plane of the carbon-based cathode active material (C-NE) can be oriented to have a predetermined angle. At this time, the planar crystal plane of the carbon-based cathode active material (C-NE) is oriented along the magnetic field lines formed between the body (112) of the upper block and the die lip (131) of the lower block. Therefore, by controlling the direction of the magnetic field lines, the angle at which the planar crystal plane of the carbon-based cathode active material (C-NE) is oriented can be controlled.

[0075] The direction of the above magnetic field lines can be controlled by adjusting the distance between the first magnet (113) included in the body (112) of the upper block and the second magnet (133) included in the die lip (131) of the lower block. For example, the plane-direction crystal plane of the carbon-based cathode active material (C-NE) can be oriented closer to vertical as the distance between the first magnet (113) and the second magnet (133) is smaller relative to the direction of travel of the first slot (151) and / or the second slot (152), and can be oriented closer to horizontal as the distance between the first magnet (113) and the second magnet (133) is larger. The present invention allows for easy control of the orientation direction of the plane-direction crystal plane of the carbon-based cathode active material (C-NE) before coating by adjusting the distance between the first magnet (113) and the second magnet (133). Accordingly, not only is the degradation of the orientation of the carbon-based cathode active material due to the viscosity of the cathode slurry or the moving speed of the current collector minimized, but the range of application for rolling conditions is also expanded, which has the advantage of allowing for free process design.

[0076] The inner surface of the body of the upper block (110) may include means for adjusting the position of the first magnet (113) so as to adjust the distance between the first magnet (113) and the second magnet (133). The shape or structure of the means may be appropriately applied within a range that does not hinder the movement of the first cathode slurry. Additionally, as shown in FIG. 2, the first slot (151) and the second slot (152) may be arranged such that the angles (θ1 and θ2) formed with respect to the surface of the current collector coated with each cathode slurry are each in the range of 50° to 130°. Specifically, considering the productivity of the cathode, the current collector may be adjusted to have a movement speed of 5 m / min to 100 m / min. However, if the moving speed of the current collector exceeds a certain speed, the carbon-based negative electrode active material (C-NE) is applied to the current collector in the double slot die (10) at an angle relatively lower than the angle at which it is oriented, so the orientation of the carbon-based negative electrode active material may be reduced. Accordingly, the present invention can minimize the reduction in the orientation angle caused by the moving speed of the current collector by adjusting each slot (151 and 152) of the double slot die (10) so that it forms an angle (θ1 and θ2) within the range described above with respect to the surface of the current collector coated with the negative electrode slurry. At this time, the angles (θ1 and θ2) formed by the first slot (151) and the second slot (152) with respect to the surface of the current collector coated with the negative electrode slurry may be different from each other. Specifically, the angles (θ1 and θ2) are each 45° to 89°; 45° to 60°; 50° to 70°; 55° to 80°; 65° to 70°; It may have a range of 55° to 70°; 60° to 75°; 65° to 80°; 70° to 115°; 80° to 110°; 91° to 135°; 91° to 120°; 91° to 115°; 91° to 110°; 95° to 105°; 95° to 125°; 100° to 125°; 101° to 115°; or 91° to 105°.

[0077] The above double slot die (10) may further include means for adjusting the angle formed by the first slot (151) and the second slot (152) with the surface of the current collector coated with a cathode slurry. Specifically, the double slot die (10) may include a tilting part (not shown) that implements rotation or tilting ('R' in FIG. 2) of the double slot die (10) on the rear portion where the blocks (110, 120 and 130) and spacers (141 and 142) are fixed. The tilting part may include an actuator such as a driving motor or a rotary cylinder. Since the tilting part can implement rotation or tilting of the double slot die (10) around a specific axis present on the rear portion of the double slot die (10), the angle (θ1 and θ2) formed by the first slot (151) and the second slot (152) with the surface of the current collector coated with a cathode slurry can be easily adjusted.

[0078] Furthermore, the cathode manufacturing system (1) according to the present invention may further include a drying unit (30) for drying a first cathode slurry and a second cathode slurry (S) applied on a current collector (C) by a double slot die (10), and a rolling unit (40) for pressing the surface of the first cathode slurry dried by the drying unit.

[0079] The drying unit (30) performs the function of removing the solvent contained in the cathode slurry to form a cathode active layer, and also performs the role of fixing the carbon-based cathode active material oriented inside the cathode slurry. To this end, the drying unit (30) can be positioned so as to dry the cathode slurry before the orientation of the plane-direction crystal plane of the carbon-based cathode active material coated on the surface of the current collector (C) is reduced.

[0080] The above drying section (30) is formed by including a wall (not shown) that blocks the surroundings except for an inlet / outlet for receiving and receiving a current collector (C) coated with cathodic slurry, and a dryer (not shown) for drying the cathodic slurry on the wall on the side where the current collector (C) coated with cathodic slurry is withdrawn.

[0081] When a current collector (C) coated with a cathode slurry enters through the inlet of the above-mentioned drying section (300), it receives energy such as light, wavelength, and heat supplied from the opposite wall. Therefore, it is desirable for the wall to be made of an insulating material so as to prevent heat loss from occurring as internal energy is transferred to the outside.

[0082] The above drying unit (30) can apply energy such as light, wavelength, or heat, and can be used without special limitations as long as it is commonly applied in the industry. For example, the above drying unit (30) can use an ultraviolet dryer, a near-infrared dryer, a far-infrared dryer, a hot air dryer, a vacuum oven, etc., alone or in combination.

[0083] The above rolling section (40) can perform the role of increasing the density of the cathode active layer formed by applying pressure to the first cathode slurry and the second cathode slurry dried by the drying section (30). At this time, the above rolling section (40) may include a first pressure roller and a second pressure roller provided on both surfaces of the current collector in which the cathode slurry is dried, so as to correspond to each other.

[0084] Specifically, referring to FIG. 4, the first pressure roller and the second pressure roller are provided to correspond to the upper and lower surfaces of the current collector, respectively, and can apply pressure in a vertical direction relative to the surface of the first cathode slurry dried on the current collector. When the pressure rollers apply pressure in a vertical direction relative to the surface of the first cathode slurry, a force is applied in a vertical direction relative to the surface of the first cathode slurry. At this time, upstream of the point where pressure is applied, resistance is generated because the force of the cathode slurry moving along the current collector and the force acting along the surface by the pressure rollers (direction of the 'dotted arrow' in FIG. 4) conflict. In this case, if the plane-direction crystal plane angle (θ3) of the carbon-based cathode active material (C-NE) is an acute angle inclined downstream along the direction of movement of the current collector relative to the surface of the current collector coated with the cathode slurry, the orientation angle of the plane-direction crystal plane of the carbon-based cathode active material contained in that area can be adjusted in the direction in which the resistance is generated. In addition, during rolling, the carbon-based cathode active material contained in the cathode slurry is subjected to compressive stress in its internal microstructure. Therefore, the compressive stress can be minimized by the carbon-based cathode active material being rearranged in the direction in which pressure is applied. At this time, the plane-direction crystal plane angle (θ4) of the carbon-based cathode active material of the rolled first cathode slurry and second cathode slurry is oriented to be nearly perpendicular to the surface of the current collector.

[0085] Meanwhile, the first pressure roller and the second pressure roller are formed from materials having different hardness values. If the hardness values ​​of the first pressure roller and the second pressure roller are the same, the final cathode sheet may be wound or bent due to the difference in elongation between the current collector (C) and the dried cathode slurry (S). Specifically, since the elongation of the current collector (C) is lower than that of the dried cathode slurry, the cathode sheet manufactured in the direction of the current collector (C) may be wound. To prevent this phenomenon, the first pressure roller and the second pressure roller may be formed from materials having different hardness values. In this case, since different pressures (or different forces) are applied to the current collector (C) and the dried cathode slurry (S) during rolling, the difference in elongation between the current collector (C) and the dried cathode slurry (S) can be reduced.

[0086] The first and second pressure rollers may be formed of metal materials and / or synthetic resins, but are not limited thereto.

[0087]

[0088] The cathode manufacturing system according to the present invention has the above-described configuration, thereby having the advantages of excellent productivity and high orientation of the carbon-based cathode active material after rolling.

[0089]

[0090] Method for manufacturing a cathode

[0091] The present invention provides a cathode manufacturing method performed using the cathode manufacturing system of the present invention described above.

[0092] The above method for manufacturing a cathode is a method for manufacturing a cathode using the cathode manufacturing system of the present invention described above, comprising the step (S1) of sequentially applying a second cathode slurry to which a magnetic field is applied and a first cathode slurry onto a current collector, wherein the first cathode slurry and the second cathode slurry each contain a carbon-based cathode active material. That is, the above manufacturing method is characterized by the simultaneous application of a magnetic field to a cathode slurry containing a carbon-based cathode active material and the application of the cathode slurry. Accordingly, the above manufacturing method has the advantage of being economical because the process is simple since crystal orientation of the carbon-based cathode active material is not performed separately after the application of the cathode slurry, and it is easy to apply to mass production due to excellent processability.

[0093] In the cathode manufacturing system of the present invention, the double slot die is arranged such that the second slot and the first slot are positioned from upstream to downstream along the direction of movement of the current collector, so that the second cathode slurry and the first cathode slurry are sequentially applied on the current collector.

[0094] The first cathode slurry and the second cathode slurry may each contain a carbon-based cathode active material self-oriented by the cathode manufacturing system as described above, and the self-orientation may be performed by applying a magnetic field before the cathode slurry is discharged onto the current collector. The carbon-based cathode active material of each cathode slurry coated on the current collector may have a planar crystal plane having a predetermined angle (specifically, θ3) with respect to the surface of the current collector coated with the cathode slurry. Here, the angle (θ3) is 45° to 89°; 45° to 60°; 50° to 70°; 55° to 80°; 65° to 70°; 55° to 70°; 60° to 75°; 65° to 80°; greater than 90° and less than or equal to 135°; 91° to 130°; 91° to 120°; Angles in the range of 91° to 110°; 95° to 130°; 95° to 120°; 110° to 135°; 105° to 120°; or 100° to 115° may be mentioned.

[0095] The above step (S1) may be performed on a current collector moving at a predetermined speed, and the moving speed may be the same as the speed at which the cathode slurry is applied to the current collector. Specifically, the current collector may move at a speed in the range of 5 to 100 m / min. For example, the current collector may move at a speed in the range of 5 to 35 m / min; 10 to 35 m / min; 20 to 35 m / min; 10 to 30 m / min; 5 to 20 m / min; 5 to 25 m / min; or 15 to 25 m / min. By moving the current collector within the above range, the present invention can prevent the cathode slurry from not being uniformly applied on the surface of the current collector due to a significantly slow application speed, while preventing a decrease in process efficiency and productivity; and can prevent the degree of orientation from being reduced due to the collapse of the crystal alignment state of the carbon-based cathode active material present in the cathode slurry caused by an excessively fast speed.

[0096] Furthermore, the method for manufacturing the cathode may further include, after the above step (S1), a step (S2) of drying the second cathode slurry and the first cathode slurry coated on the current collector to form a second cathode active layer and a first cathode active layer, and a step (S3) of rolling the formed first cathode active layer and the second cathode active layer.

[0097] The above step (S2) refers to a process of fixing the carbon-based cathode active material contained in each cathode slurry onto a current collector by drying the coated first cathode slurry and the second cathode slurry. This step (S2) is not particularly limited and can be applied as long as it is a method that can fix the carbon-based cathode active material while minimizing the loss of orientation of the carbon-based cathode active material of the cathode slurry coated on the current collector with respect to the surface of the current collector. Specifically, the drying may be performed by applying energy such as light, wavelength, or heat, and to this end, it may be performed by using an ultraviolet dryer, a near-infrared dryer, a far-infrared dryer, a hot air dryer, a vacuum oven, etc., either alone or in combination.

[0098] The above step (S3) refers to a process of increasing the density of the formed first cathode active layer and the second cathode active layer, and the process can be performed by applying pressure to the surface of the first cathode active layer.

[0099] The above pressure can be applied by a first pressure roller and a second pressure roller provided on both surfaces of a current collector on which a first cathode active layer and a second cathode active layer are formed, in a mutually corresponding manner.

[0100] The first pressure roller and the second pressure roller are respectively provided to correspond to the upper and lower surfaces of the current collector, and can apply pressure in a vertical direction relative to the surface of the first cathode slurry dried on the current collector. In this process, the orientation angle of the crystal planes in the plane direction of the carbon-based cathode active material contained in each cathode active layer can increase to be close to vertical due to the applied pressure.

[0101] That is, the method for manufacturing a cathode according to the present invention includes the process of applying a cathode slurry oriented at a predetermined angle in step (S1) onto a current collector to orient the plane-direction crystal plane of a carbon-based cathode active material at an angle (θ3) within a predetermined range relative to the surface of the current collector on which the cathode slurry is applied, and tilting the plane-direction crystal plane of the carbon-based cathode active material by applying pressure to the cathode active layer after drying in step (S3). Accordingly, the method for manufacturing a cathode can manufacture a cathode in which the plane-direction crystal plane of the carbon-based cathode active material is oriented at a high angle (θ4) close to vertical.

[0102] For example, when X-ray diffraction analysis (XRD) is performed on the first cathode active layer formed in step (S2) and the first cathode active layer formed in step (S3), the orientation degree (OI) represented by the following Equation 1 may be greater than that of the first cathode active layer formed in step (S2) before rolling and the first cathode active layer of the rolled step (S3):

[0103] [Equation 1]

[0104] OI = I 004 / I 110

[0105] In Equation 1,

[0106] I 004 represents the area of ​​the peak indicating the (004) crystal plane during X-ray diffraction spectroscopy (XRD) measurement of the cathode active layer, and

[0107] I 110 This represents the area of ​​the peak indicating the crystal plane (110) when X-ray diffraction spectroscopy (XRD) is measured for the cathode active layer.

[0108]

[0109] The orientation degree (OI) of the carbon-based cathode active material defined by Equation 1 above can serve as a relative indicator representing the degree to which the crystal planes of the carbon-based cathode active material are oriented in a certain direction, specifically with respect to the surface of the cathode current collector, when measured by X-ray diffraction (XRD). The cathode active layer exhibits peaks for graphite, which is the carbon-based cathode active material, at 2θ = 26.5±0.2°, 42.4±0.2°, 43.4±0.2°, 44.6±0.2°, 54.7±0.2°, and 77.5±0.2° when measured by X-ray diffraction. These peaks represent the (002) plane, (100) plane, (101)R plane, (101)H plane, (004) plane, and (110) plane, respectively. In addition, the peak appearing at 2θ=43.4±0.2° can be seen as an overlap between the (101)R plane of the carbon-based cathode active material and the (111) plane of the current collector, for example, copper (Cu).

[0110] The orientation degree (OI) of the carbon-based negative electrode active material can be measured through the ratio of the intensity of the peak at 2θ=54.7±0.2° representing the (004) plane and the peak at 2θ=77.5±0.2° representing the (110) plane. Here, the peak at 2θ=54.7±0.2° represents the (110) plane among the crystal planes of the carbon-based negative electrode active material that has an inclination with respect to the negative current collector, and the (110) plane represents the ab-axis crystal plane, which is the plane-direction crystal plane of the carbon-based negative electrode active material. Therefore, the orientation degree (OI) can mean that the closer the value is to 0, the closer the inclination with respect to the surface of the negative current collector is to 90°, and the greater the value, the closer the inclination with respect to the surface of the negative current collector is to 0° or 180°.

[0111] The cathode manufactured according to the present invention may be rolled so that the orientation degree (OI) represented by Formula 1 is 0.5 to 10 when X-ray diffraction analysis is performed on the first cathode active layer. Specifically, the first cathode active layer of the cathode may satisfy the orientation degree (OI) range of 0.5 to 9; 0.5 to 8; 0.5 to 6; 0.5 to 5; 0.5 to 3.5; 0.5 to 2.9; 1 to 10; 3 to 10; 5 to 10; 7 to 10; 2 to 6; 2 to 8; 4 to 9; 3 to 9; 3.5 to 6.0; 4.5 to 9.0; 4.2 to 8.9; or 2.1 to 5.5. This means that the carbon-based cathode active material of the above-mentioned cathode is aligned to have an angle of 70° or more, 70~80°, 70~90°, 80~90°, 75~85°, 70~85°, or 85~90° with respect to the cathode current collector.

[0112] In comparison, the first cathode active layer that is dried and not rolled in the above step (S2) has a relatively low angle between the plane-direction crystal planes of the carbon-based cathode active material and the current collector, so the orientation degree (OI) can have a larger value than that of the first cathode active layer that is rolled.

[0113]

[0114] Meanwhile, the carbon-based negative electrode active material contained in the first negative electrode slurry and the second negative electrode slurry may include materials that are conventionally applied as carbon-based negative electrode active materials for secondary batteries. Specifically, the carbon-based negative electrode active material refers to a material having carbon atoms as its main component, and such carbon-based negative electrode active material may include graphite. The graphite may include one or more of natural graphite and artificial graphite, but preferably may include natural graphite or a mixture of natural graphite and artificial graphite.

[0115] The carbon-based cathode active material is preferably a spherical graphite assembly formed by aggregating a plurality of flake-shaped graphites. Examples of flake-shaped graphites include natural graphite, artificial graphite, mesophase calcined carbon (bulk mesophase) made from tar and pitch, and graphitized cokes (raw coke, green coke, pitch coke, needle coke, petroleum coke, etc.). In particular, it is preferable to use a plurality of natural graphites with high crystallinity to form the assembly. Additionally, one graphite assembly may be formed by aggregating 2 to 100 flake-shaped graphites, preferably 3 to 20.

[0116] The carbon-based cathode active material may be included as a main component of the first cathode slurry and the second cathode slurry and may be included in a high content. Specifically, the carbon-based cathode active material may be included in an amount of 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, 95 wt% or more, 75 wt% to 99 wt%, 80 wt% to 98 wt%, or 90 wt% to 99 wt% based on the total weight of each cathode slurry.

[0117] In addition, the first cathode slurry and the second cathode slurry may further include a conductive material, a binder, a thickener, etc., in addition to the carbon-based cathode active material, and these may be applied as materials commonly used in the industry.

[0118]

[0119] The method for manufacturing a cathode according to the present invention, by having the configuration described above, enables the manufacturing of a cathode with high productivity. Furthermore, the manufactured cathode has the advantage of not only having excellent energy density but also excellent orientation of the carbon-based cathode active material.

[0120]

[0121] The technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

[0122]

[0123] [Explanation of the symbol]

[0124] 1: Cathode manufacturing system

[0125] 10: Dual slot die

[0126] 20: Transfer section 21a, 21b, 21c: Rollers of the roll-to-roll device

[0127] 30: Drying section 40: Rolling section

[0128] 110: Upper block 120: Middle block

[0129] 130: Lower block

[0130] 111: Upper block's die-rip 131: Lower block's die-rip

[0131] 112: Body of the upper block 132: Body of the lower block

[0132] 113: Magnet included in the body of the upper block

[0133] 133: Magnet included in the die rib of the lower block

[0134] 141 and 142: First spacer and second spacer

[0135] 151 and 152: 1st slot and 2nd slot

[0136] C: Entire house

[0137] C-NE: Carbon-based negative electrode active material

[0138] S: Cathode slurry

Claims

1. A transport unit that moves the entire house, and It includes a dual slot die comprising an upper block, an intermediate block, and a lower block, a first slot provided through the gap between the upper block and the intermediate block for discharging a first cathode slurry, and a second slot provided through the gap between the intermediate block and the lower block for discharging a second cathode slurry; A cathode manufacturing system in which the upper block, middle block, and lower block are divided into a die lip forming a discharge port at each tip and a body extending from the die lip, wherein the body of the upper block and the die lip of the lower block exhibit magnetism of different polarities.

2. In Paragraph 1, A cathode manufacturing system in which the body of the upper block and the die lip of the lower block each comprise one or more types of magnets among permanent magnets and electromagnets.

3. In Paragraph 2, A cathode manufacturing system in which the distance between the magnet included in the body of the upper block and the magnet included in the die lip of the lower block is adjustable.

4. In Paragraph 1, A cathode manufacturing system in which the body of the upper block and the die lip of the lower block each have a magnetic flux density in the range of 0.05T to 1.0T.

5. In Paragraph 1, The above double slot die is a cathode manufacturing system in which the second slot and the first slot are positioned from upstream to downstream along the direction of movement of the current collector.

6. In Paragraph 1, A cathode manufacturing system in which the first slot and the second slot are each arranged to have an angle ranging from 50° to 130° relative to the surface of a current collector coated with a cathode slurry.

7. In Paragraph 6, A cathode manufacturing system characterized in that the above-described double slot die is configured to be tiltable so as to be able to adjust the angle formed by the first slot and the second slot with the surface of the current collector.

8. In Paragraph 1, The above cathode manufacturing system is, A drying unit for drying the first cathode slurry and the second cathode slurry applied on the current collector by the above-mentioned double slot die, and A cathode manufacturing system further comprising a rolling section that pressurizes the surface of the first cathode slurry dried by the above drying section.

9. In Paragraph 8, The above rolling section is a cathode manufacturing system that applies pressure in a vertical direction relative to the surface of a dried first cathode slurry.

10. A step (S1) of sequentially applying a second cathode slurry and a first cathode slurry, to which a magnetic field is applied, onto a moving current collector using a cathode manufacturing system according to claim 1, and A method for manufacturing a cathode in which the first cathode slurry and the second cathode slurry each comprise a carbon-based cathode active material.

11. In Paragraph 10, After the above step (S1), A step (S2) of drying the second cathode slurry and the first cathode slurry applied on the current collector to form a second cathode active layer and a first cathode active layer, and A method for manufacturing a cathode further comprising the step (S3) of rolling the formed first cathode active layer and the second cathode active layer.

12. In Paragraph 10, The first cathode active layer has an orientation degree (OI) before rolling that is greater than the orientation degree (OI) after rolling, and The above orientation degree (OI) is a method for manufacturing a cathode represented by the following Equation 1: [Equation 1] OI = I 004 / I 110 In Equation 1, I 004 represents the area of ​​the peak indicating the (004) crystal plane during X-ray diffraction spectroscopy (XRD) measurement of the cathode active layer, and I 110 This represents the area of ​​the peak indicating the crystal plane (110) when X-ray diffraction spectroscopy (XRD) is measured for the cathode active layer.

13. In Paragraph 12, A method for manufacturing a cathode in which the first cathode active layer has an orientation degree (OI) in the range of 0.5 to 10 after rolling.

14. In Paragraph 10, The above-mentioned current collector is a method for manufacturing a cathode that moves at a speed in the range of 5 m / min to 100 m / min.

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