Device for manufacturing negative electrode of secondary battery

Abstract

The present invention relates to an apparatus for manufacturing a negative electrode of a secondary battery and a method for manufacturing a negative electrode using the same. The negative electrode manufacturing apparatus includes: a double-groove mold including an upper block, an intermediate block, a lower block, a first groove, and a second groove; the first groove and the second groove are used for passing through each gap between the upper block and the middle block and each gap between the middle block and the lower block to discharge negative electrode slurry; and a coating roller, in which the upper lip, the middle lip, and the lower lip provided at the front end portion of each block apply magnetic fields of the same polarity, and the coating roller applies a magnetic field of opposite polarity to the magnetic field of each lip. Therefore, the carbon-based negative electrode active material in the discharged negative electrode slurry can be coated in a state in which the crystal face thereof is oriented approximately perpendicular to the surface of the negative electrode current collector. Therefore, the manufactured negative electrode has an excellent degree of orientation with respect to a carbon-based negative electrode active material, and is easy to mass-produce.

Description

Technical Field

[0001] The present invention relates to a negative electrode manufacturing device for a secondary battery and a method for manufacturing a negative electrode of a secondary battery using the negative electrode manufacturing device.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0175563 filed on December 15, 2022, and the entire contents of this Korean Patent Application are incorporated herein by reference. Background Art

[0003] Recently, secondary batteries are widely used not only in small devices such as portable electronic devices but also in medium and large-sized devices such as battery packs or power storage devices in hybrid or electric vehicles.

[0004] This secondary battery refers to a rechargeable and dischargeable power generation device including a stacked structure of a positive electrode / separator / negative electrode. Typically, the positive electrode includes a lithium metal oxide as a positive electrode active material, and the negative electrode includes a carbon-based negative electrode active material (such as graphite), so that when the secondary battery is charged, lithium ions emitted from the positive electrode are adsorbed into the carbon-based negative electrode active material of the negative electrode, and when the secondary battery is discharged, lithium ions contained in the carbon-based negative electrode active material are adsorbed into the lithium metal oxide of the positive electrode, and charging and discharging are repeated.

[0005] The negative electrode active material used in the negative electrode includes graphite materials such as natural graphite, artificial graphite, etc. This graphite has a layered structure and is formed by stacking multiple layers, in which carbon atoms form a network structure distributed in a planar shape. During charging, lithium ions can invade from the edges of these graphite layers (layer overlap sides) and diffuse between the layers, and during discharge, lithium ions can be deintercalated and released from the edges of the layers. In addition, since graphite has a lower resistance in the lateral direction of the layer than in the stacking direction of the layer, a conduction path for turning electrons is formed along the lateral direction of the layer.

[0006] In this regard, in lithium secondary batteries using graphite, a technique has been conventionally proposed to magnetically orient the graphite contained in the negative electrode to improve the charging performance of the negative electrode. Specifically, it has a configuration in which, when the negative electrode is formed, the [0,0,2] crystal plane of the graphite is oriented in a magnetic field so that it is approximately horizontal relative to the current collector and fixed therein. In this case, since the edge of the graphite layer faces the positive electrode active layer, the insertion and extraction of lithium ions can be smoothly carried out, and the conduction path of the electrons is shortened, which can improve the electronic conductivity of the negative electrode, thereby improving the charging performance of the battery.

[0007] By applying a negative electrode slurry containing graphite on the current collector and applying a magnetic field to the undried negative electrode slurry, the graphite can be induced to produce such an orientation. However, in the actual mass production of negative electrodes, considering the production speed, it is difficult to ensure that there is enough time to apply the magnetic field to induce the graphite alignment of the negative electrode slurry. In addition, if the intensity of the magnetic field applied to the negative electrode slurry applied to the electrode sheet is increased to solve this problem, the magnetic field will attract the graphite at the end of the magnetic field, and the orientation of the graphite aligned perpendicular to the metal sheet will collapse, resulting in poor orientation of the graphite in the final negative electrode active layer.

[0008] Therefore, there is a need for a negative electrode manufacturing technology that can achieve a high degree of orientation of graphite and is suitable for mass production of negative electrodes for secondary batteries.

[0009] [Prior art literature]

[0010] [Patent Document]

[0011] Korean Patent Publication No. 10-2018-0048131 Summary of the invention

[0012] Technical issues

[0013] The object of the present invention is to provide a negative electrode manufacturing technology that can achieve a high crystal orientation degree of a carbon-based negative electrode active material such as graphite contained in a negative electrode active layer and is suitable for mass production of negative electrodes for secondary batteries.

[0014] Technical Solution

[0015] In order to solve the above problems, in one embodiment, the present invention provides:

[0016] A device for manufacturing an electrode sheet, on which a negative electrode slurry containing a carbon-based negative electrode active material is applied,

[0017] The negative electrode manufacturing device for a secondary battery comprises:

[0018] A double-groove mold, the double-groove mold comprising an upper block, a middle block, and a lower block, and a first groove and a second groove, the first groove being arranged to pass through a gap between the upper block and the middle block and discharge a first negative electrode slurry, the second groove being arranged to pass through a gap between the middle block and the lower block and discharge a second negative electrode slurry; and

[0019] a coating roller that is opposite to the first groove and the second groove of the double groove mold and conveys the electrode sheet coated with the negative electrode slurry discharged from each groove,

[0020] wherein the upper block, the middle block and the lower block include an upper lip, a middle lip and a lower lip forming an outlet at their respective front ends, and the upper lip, the middle lip and the lower lip exhibit magnetic properties of the same polarity, and

[0021] The coating roller exhibits a magnetic polarity opposite to that of the upper lip.

[0022] In this case, the upper lip and the lower lip may have a structure including at least one of a permanent magnet and an electromagnet so that a magnetic field having an intensity of 500 G to 3000 G is applied when the negative electrode slurry is discharged.

[0023] In addition, the double slot die can satisfy the following equation 1:

[0024] [Equation 1]

[0025] G lip / G roll ≤1

[0026] (In Equation 1,

[0027] G lip Refers to the magnetic field strength applied to the upper lip, middle lip and lower lip (unit: G),

[0028] G roll refers to the magnetic field strength applied to the coating roller (unit: G).

[0029] In addition, the negative electrode manufacturing apparatus may further include a drying part for drying the negative electrode slurry applied to the electrode sheet.

[0030] Also, the drying part may be provided at a position such that the negative electrode slurry discharged from the double-grooved mold can reach the electrode sheet within 20 seconds from the time when the negative electrode slurry is applied.

[0031] Furthermore, in one embodiment,

[0032] A method for manufacturing a negative electrode for a secondary battery, comprising: applying a negative electrode slurry to which magnetism is applied to an electrode sheet using the negative electrode manufacturing apparatus according to the present invention,

[0033] Wherein, the negative electrode slurry contains carbon-based negative electrode active material.

[0034] In this case, the average thickness of the negative electrode slurry applied to the electrode sheet may be greater than a separation distance between the grooves of the double groove mold provided in the negative electrode manufacturing apparatus and the coating roller, and the average thickness of the negative electrode slurry applied to the electrode sheet may be 100 μm or more.

[0035] In addition, applying the negative electrode slurry to the electrode sheet may be performed at a speed of 5 m / min to 100 m / min.

[0036] In addition, applying the negative electrode slurry to the electrode sheet may further include drying the applied negative electrode slurry to form a negative electrode active layer after applying the negative electrode slurry to the electrode sheet.

[0037] Here, the alignment degree of the carbon-based negative electrode active material of the negative electrode active layer with respect to the surface of the electrode sheet may be 0.9 or less, as expressed by the following Equation 2:

[0038] [Equation 2]

[0039] OI=I 004 / I 110

[0040] In equation 2,

[0041] I 004 It refers to the area of ​​the peak representing the [0,0,4] crystal plane in the X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer.

[0042] I 110 Refers to the area of ​​the peak indicating the [1,1,0] crystal plane in X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer.

[0043] Beneficial Effects

[0044] The negative electrode manufacturing device for a secondary battery according to the present invention can apply the carbon-based negative electrode active material in the negative electrode slurry in a state of being oriented nearly perpendicular to the current collector surface. Therefore, the advantage of the manufactured negative electrode is that not only the carbon-based negative electrode active material has an excellent orientation degree, but also it is easy to apply to mass production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic cross-sectional view showing a negative electrode manufacturing apparatus for a secondary battery according to the present invention.

[0046] Figure 2 is a perspective view showing the structure of a double-die coater provided in the negative electrode manufacturing apparatus for a secondary battery according to the present invention.

[0047] Figure 3 2 is a conceptual diagram showing the principle of applying a carbon-based negative electrode active material of a negative electrode slurry to an electrode sheet in a self-aligned state by a double die coater according to the present invention. DETAILED DESCRIPTION

[0048] The present invention can have various modifications and various embodiments, so specific embodiments thereof will be described in detail below.

[0049] However, it should be understood that the present invention is not limited to the specific embodiments, and includes all modifications, equivalents, or alternatives within the spirit and technical scope of the present invention.

[0050] The terms "comprising", "including" and "having" as used herein indicate the presence of features, numbers, steps, actions, parts or components, or a combination thereof, described in the specification, and it should be understood that the possibility of the presence or addition of one or more other features, numbers, steps, actions, parts, components, or a combination thereof is not precluded.

[0051] Furthermore, in the present invention, when a part of a layer, film, region, plate, etc. is disposed on another part, this includes not only a case where one part is directly disposed on another part, but also a case where another part is interposed therebetween. Conversely, when a part of a layer, film, region, plate, etc. is disposed below another part, this includes not only a case where one part is directly disposed below another part, but also a case where another part is interposed therebetween. Furthermore, in the present application, “on…” may include not only a case where it is disposed on an upper part, but also a case where it is disposed on a lower part.

[0052] In addition, in the present invention, "comprising as a main component ..." may refer to a defined component comprising at least 50 wt.% (or at least 50 vol.%), at least 60 wt.% (or at least 60 wt.%), at least 70 wt.% (or at least 70 vol.%), at least 80 wt.% (or at least 80 vol.%), at least 90 wt.% (or at least 90 vol.%), or at least 95 wt.% (or at least 95 vol.%) relative to the total weight (or total volume) of the negative electrode active material. For example, "comprising graphite as a main component of the negative electrode active material" may refer to graphite comprising at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.%, based on the total weight of the negative electrode active material, and in some cases may refer to the entire negative electrode active material being graphite, comprising at least 100 wt.% of graphite.

[0053] In addition, in the present invention, the "lip portion" is a region including the upper lip of the upper block, the middle lip of the middle block, and the lower lip of the lower block, and may include a spacing space formed between the plurality of lips, that is, a region of each lip disposed in the first groove and the second groove. Similarly, in the present invention, the "body portion" refers to a region including the upper body of the upper block, the middle body of the middle block, and the lower body of the lower block. The body portion may include a spacing space formed between the bodies, that is, a region of each body disposed in the first groove and the second groove.

[0054] Hereinafter, the present invention will be described in more detail.

[0055] Negative electrode manufacturing device for secondary battery

[0056] In one embodiment, the present invention provides,

[0057] A device for manufacturing an electrode sheet, on which a negative electrode slurry containing a carbon-based negative electrode active material is applied, the negative electrode manufacturing device for a secondary battery comprising:

[0058] A double-groove mold, the double-groove mold comprising an upper block, a middle block, and a lower block, and a first groove and a second groove, the first groove being arranged to pass through a gap between the upper block and the middle block and discharge a first negative electrode slurry, the second groove being arranged to pass through a gap between the middle block and the lower block and discharge a second negative electrode slurry; and

[0059] a coating roller that is opposite to the first groove and the second groove of the double groove mold and conveys the electrode sheet coated with the negative electrode slurry discharged from each groove,

[0060] wherein the upper block, the middle block and the lower block include an upper lip, a middle lip and a lower lip forming an outlet at their respective front ends, and the upper lip, the middle lip and the lower lip exhibit magnetic properties of the same polarity, and

[0061] The coating roller exhibits a magnetic polarity opposite to that of the upper lip.

[0062] The negative electrode manufacturing apparatus for a secondary battery according to the present invention is an apparatus for manufacturing a negative electrode used in a secondary battery, and has a configuration of manufacturing an electrode sheet by applying a negative electrode slurry containing a carbon-based negative electrode active material to a current collector.

[0063] Specifically, Figure 1 1 is a schematic cross-sectional view of the structure of a negative electrode manufacturing device for a secondary battery according to the present invention. Referring to FIG. 1 , the negative electrode manufacturing device 10 includes a double groove mold 100 and a coating roller 200, and has a structure in which a negative electrode slurry is applied to a surface while an electrode sheet 300 is moved by the rotation of the coating roller 200.

[0064] The double groove mold 100 has a first groove 151 and a second groove 152, so that two types of negative electrode slurries (same or different) can be double applied to the current collector. Figure 2 As shown in , the first groove 151 may be formed between positions where the upper mold 110 and the middle mold 120 face each other, and the second groove 152 may be formed between positions where the middle mold 120 and the lower mold 130 face each other.

[0065] For example, the double groove mold 100 may include a first spacer 141 and a second spacer 142, which are sequentially inserted between the upper mold 110 and the middle mold 120 and between the middle mold 120 and the lower mold 120, so that a gap is provided therebetween to form a channel, in other words, to form grooves 151 and 152 through which the negative electrode slurry can fluidly move. In this case, the upper and lower heights of the grooves may be determined by the thickness (in the Y-axis direction) of the first spacer 141 and / or the second spacer 142 (reflecting the gap between each mold).

[0066] The thickness of the first spacer 141 and / or the second spacer 142 may be controlled according to the use or capacity of the secondary battery. Specifically, the thickness of each spacer 141 and 142 may be independently 50 μm to 2000 μm, and more specifically 50 μm to 1500 μm; 500 μm to 1200 μm; 800 μm to 1200 μm; 80 μm to 200 μm; 200 μm to 500 μm; or 400 μm to 700 μm.

[0067] In addition, the first spacer 141 and / or the second spacer 142 may have an opening 130a in which the first area is cut, and may be inserted in all frame areas of the upper mold 110, the middle mold 120, and the lower mold 130 except for one of the corresponding opposing frame areas. Therefore, a discharge groove, in other words, a first groove 151 and a second groove 152, is formed only between the front ends of the upper mold 110, the middle mold 120, and the lower mold 130, through which the negative electrode slurry can be discharged to the outside. Here, each front end of the upper mold 110, the middle mold 120, and the lower mold 130 includes an upper lip 111, a middle lip 121, and a lower lip 131, and the discharge grooves 151 and 152 for discharging the negative electrode slurry are formed by the intervals between the corresponding lips 111, 121, and 131.

[0068] In addition, the first and second separators 141 and 142 are preferably made of a material having sealing properties to prevent the negative electrode slurry from leaking into a gap between each mold 110 , 120 , and 130 except for a region where the first and second grooves 151 and 152 are formed by functioning as a gasket.

[0069] Meanwhile, the upper mold 110, the middle mold 120 and the lower mold 130 may include an upper lip 111, a middle lip 121 and a lower lip 131 at their respective front ends, and include an upper body 112, a middle body 122 and a lower body 132, the upper body 112, the middle body 122 and the lower body 132 extending from each lip and in close contact with the first spacer 141 and / or the second spacer 142 to form a channel through which the negative electrode slurry fluid can move.

[0070] In addition, the upper lip 111, the middle lip 121, and the lower lip 131 may exhibit magnetism. Specifically, the upper lip 111, the middle lip 121, and the lower lip 131 may exhibit magnetism having the same polarity, so a magnetic field in the same direction as the negative electrode slurry discharge direction may be formed in the first groove 151 and the second groove 152 formed by each of the lips 111, 121, and 131.

[0071] like Figure 3 As shown in , if the path for discharging and applying the negative electrode slurry is divided into an unoriented section A and an oriented section B, the carbon-based negative electrode active material (CM, such as graphite) of the negative electrode slurry is not affected by the magnetic field in the unoriented section A (in other words, I: body part) including the spacing space between the bodies 112, 122 and 132 of each mold, and thus moves in a state with a high degree of freedom. However, in the oriented section B (in other words, II: lip part) including the spacing space between the upper lip 111, the middle lip 121 and the lower lip 131 exhibiting the same polarity of magnetism, due to the action of the repulsive force, a magnetic field direction (MD) can be formed in the same direction as the negative electrode slurry discharge direction. Therefore, before the negative electrode slurry is applied to the negative electrode collector, the carbon-based negative electrode active material (CM) (in other words, graphite) contained in the negative electrode slurry can be oriented so that the [0,0,2] crystal plane is approximately horizontal relative to the negative electrode collector. Since the graphite thus oriented is applied to the current collector while maintaining the orientation (in other words, corresponding to III: coating region), after the negative electrode slurry is applied, the graphite can have a high degree of orientation without applying any magnetic field.

[0072] In this case, the upper lip 111, the middle lip 121, and the lower lip 131 may include an electromagnet and / or a permanent magnet to indicate magnetism. The electromagnet may include both a DC electromagnet and an AC electromagnet. In addition, the permanent magnet may include a magnet having ferromagnetic properties and a magnet having soft magnetic properties, including NdFeB-based magnets, SmCo-based magnets, ferrite magnets, Alnico magnets, FeCrCo-based magnets, Bond magnets (Nd-Fe-B, Sm-Fe-N, Sm-Co, ferrite), etc.

[0073] In addition, since the negative electrode manufacturing device applies a magnetic field before applying the negative electrode slurry to the electrode sheet, a weaker magnetic field can be applied compared to the case where the magnetic field is applied after the negative electrode slurry is applied to the electrode sheet. The magnetic field strength at this time can meet the predetermined range. In other words, the upper lip 111, the middle lip 121, and the lower lip 131 can be subjected to a magnetic field that meets the predetermined intensity range when the negative electrode slurry is discharged. Specifically, the upper lip 111, the middle lip 121, and the lower lip 131 can be subjected to the same magnetic field. In this case, the applied magnetic field can have a strength of 500G to 3000G (Gauss), or more specifically, 500G to 2500G; 500G to 2000G; 500G to 1500G; 1000G to 2000G; 2000G to 2500G; 2000G to 3000G; 500G to 1500G; or 500G to 900G.

[0074] The present invention can achieve uniform crystal orientation of the carbon-based negative electrode active material before the negative electrode slurry is discharged through the first groove 151 and the second groove 152 by adjusting the magnetic field strength applied to the upper lip 111, the middle lip 121 and the lower lip 131 to the above range. In addition, the negative electrode manufacturing device can maintain the orientation degree so that the carbon-based negative electrode active material with uniform crystal orientation is applied to the current collector without changing the orientation degree after discharge. In addition, the present invention can prevent the magnetic field strength applied to the upper lip 111, the middle lip 121 and the lower lip 131 from exceeding the above range, so as not to narrow the separation distance between the lips and make the discharge of the negative electrode slurry difficult.

[0075] The first groove 151 and the second groove 152 may be positioned so that the negative electrode slurry is discharged perpendicularly to the surface of the negative electrode current collector. To this end, the double groove mold 100 may be positioned perpendicularly to the surface of the electrode sheet 300. Preferably, as Figure 1 As shown in , the negative electrode manufacturing device of the present invention may include a rotatably arranged coating roller 200 arranged to face the first groove 151 and the second groove 152 of the double-groove mold 100, so that the electrode sheet 300 or the negative electrode collector can move with the rotation of the coating roller 200, and the negative electrode slurry can be applied to its surface.

[0076] In addition, the coating roller 200 may exhibit magnetism on its surface to allow the carbon-based negative electrode active material of the negative electrode slurry applied to the electrode sheet 300 to maintain the orientation inside the double groove mold 100. In this case, the magnetism may have a polarity different from that of the lips 111, 121, and 131 of the double groove mold 100. The present invention can prevent the crystal orientation of the carbon-based negative electrode active material applied to the surface of the electrode sheet 300 from being reduced by imparting magnetism having a polarity different from that of the lips 111, 121, and 131 of the double groove mold 100 to the surface of the coating roller 200. Such magnetism can be achieved by introducing one or more of a permanent magnet and an electromagnet to the surface of the coating roller 200.

[0077] In addition, the magnetic field applied to the coating roller 200 may be stronger than the magnetic field strength applied to the lips 111, 121 and 131 of the double groove mold 100, so that the crystal orientation of the carbon-based negative electrode active material in the negative electrode slurry remains unchanged and can be applied to the electrode sheet 300 or the negative electrode current collector. As an example, the coating roller 200 may satisfy the following equation 1:

[0078] [Equation 1]

[0079] G lip / G roll ≤1

[0080] In equation 1,

[0081] G lip Refers to the magnetic field strength applied to the upper lip, middle lip and lower lip (unit: G),

[0082] G roll Refers to the magnetic field strength applied to the coating roller (unit: G).

[0083] When a strong magnetic field is applied to the lip of the double groove mold 100, the repulsive force between the upper lip 111, the middle lip 121 and the lower lip 131 acts strongly, and the height of the groove is uneven, so the magnetic field applied to the lip of the double groove mold 100 is controlled to meet the predetermined range as described above. However, in this case, the crystal orientation of the carbon-based negative electrode active material oriented according to the fluid momentum and / or direction of the negative electrode slurry may change when the negative electrode slurry is discharged. Therefore, the negative electrode manufacturing device of the present invention has a configuration in which a magnetic field is applied to a coating roller 200 disposed on the other side of an electrode sheet 300 (or a current collector), and the electrode sheet 300 is applied with a negative electrode slurry having a polarity opposite to that of the magnetic field applied at the lip, but the magnitude of the applied magnetic field is greater than the magnitude of the magnetic field applied at the lip. Therefore, the carbon-based negative electrode active material can be applied to the surface of the electrode sheet 300 or the negative electrode current collector so that the crystal plane is close to vertical. At this time, the coating roller 200 can satisfy the above equation 1, where G lip / G rollis 1 or less (in other words, G lip / G roll ≤1), specifically, 0.1 to 1 (in other words, 0.1≤G lip / G roll ≤1), 0.2 to 0.9 (i.e., 0.2≤G lip / G roll ≤0.9), 0.4 to 0.9 (i.e., 0.4≤G lip / G roll ≤0.9), 0.3 to 0.6 (i.e., 0.3≤G lip / G roll ≤0.6), 0.5 to 0.9 (i.e., 0.5≤G lip / G roll ≤0.9), 0.51 to 0.99 (i.e., 0.51 ≤ G lip / G roll ≤0.99), 0.70 to 0.99 (i.e., 0.70≤G lip / G roll ≤0.99), 0.90 to 0.99 (i.e., 0.90≤G lip / G roll ≤0.99), 0.6 to 0.8 (i.e., 0.6≤G lip / G roll ≤0.8) or 0.45 to 0.75 (i.e., 0.45 ≤ G lip / G roll ≤0.75).

[0084] The present invention, by providing a coating roller 200 that satisfies mode 1 within the above-mentioned range, can prevent the crystal planes of the carbon-based negative electrode active material from being oriented at a low angle relative to the surface of the electrode sheet 300 and the negative electrode collector due to the insignificant magnetic field applied by the coating roller 200, and at the same time prevent the productivity of cathode manufacturing from being reduced due to excessively high magnetic field applied intensity.

[0085] In addition, the negative electrode manufacturing device 10 according to the present invention may further include a drying section (not shown) for drying the negative electrode slurry applied to the electrode sheet 300, wherein the drying section is arranged so that the negative electrode slurry discharged from the double-grooved mold 100 reaches the electrode sheet within 20 seconds (specifically, 0.01 seconds to 20 seconds; 0.01 seconds to 15 seconds; 0.01 seconds to 10 seconds; or 0.01 seconds to 5 seconds) from the time of application to the electrode sheet.

[0086] The drying unit performs the function of removing the solvent contained in the negative electrode slurry to form the negative electrode active layer, and also performs the function of fixing the carbon-based negative electrode active material oriented inside the negative electrode slurry. To this end, the arrangement position of the drying unit can dry the negative electrode slurry before the crystal orientation of the carbon-based negative electrode active material applied to the surface of the electrode sheet 300 is reduced.

[0087] In addition, the drying part is formed to include a wall (not shown) that blocks the periphery except for the inlet and outlet for entering and exiting the electrode sheet 300 to which the negative electrode slurry is applied, and a dryer (not shown) for drying the electrode sheet on the wall on the side from which the electrode sheet 300 to which the negative electrode slurry is applied comes out.

[0088] When the electrode sheet 300 applied with the negative electrode slurry enters through the entrance of the drying part, it receives energy such as light, wavelength, heat, etc. supplied from the opposite wall. Therefore, the wall is preferably made of an insulating material so that the energy inside can be transferred to the outside and heat loss is prevented.

[0089] In addition, the dryer can be used without particular limitation as long as it can apply energy such as light, wavelength, heat, etc. and is conventionally used in the art. For example, the dryer can be an ultraviolet dryer, a near infrared dryer, a far infrared dryer, a hot air dryer, a vacuum oven, etc., alone or in combination.

[0090] The negative electrode manufacturing device according to the present invention has the above-mentioned configuration to induce the crystal orientation of the carbon-based negative electrode active material before the negative electrode slurry is discharged onto the negative electrode sheet, so that the carbon-based negative electrode active material can be applied in a state where the carbon-based negative electrode active material is oriented close to perpendicular to the surface of the negative electrode current collector. Therefore, the carbon-based negative electrode active material of the manufactured negative electrode has an excellent degree of orientation. In addition, since the above negative electrode manufacturing device does not require a separate orientation process to orient the carbon-based negative electrode active material after applying the negative electrode slurry, it has the advantages of not requiring additional equipment to manufacture the negative electrode and being easy to apply to mass production processes.

[0091] Method for manufacturing negative electrode for secondary battery

[0092] In one embodiment, the present invention also provides,

[0093] A method for manufacturing a negative electrode for a secondary battery, comprising: applying a negative electrode slurry to which magnetism is applied to an electrode sheet using a negative electrode manufacturing apparatus according to the present invention,

[0094] The negative electrode slurry contains carbon-based negative electrode active materials.

[0095] The method for manufacturing a negative electrode for a secondary battery according to the present invention is a method for manufacturing a negative electrode using the negative electrode manufacturing device of the present invention described above, comprising applying a magnetic negative electrode slurry to an electrode sheet. In other words, the manufacturing method is characterized in that a magnetic field is applied to a negative electrode slurry containing a carbon-based negative electrode active material while applying the negative electrode slurry to an electrode sheet (i.e., a current collector). Therefore, the advantage of the above manufacturing method is that the crystal orientation of the carbon-based negative electrode active material is not performed separately after applying the negative electrode slurry, so it is economical due to the simple process, and it is easy to apply to mass production due to its excellent processability.

[0096] Here, the negative electrode slurry may contain a carbon-based negative electrode active material, which is magnetically oriented by means of the negative electrode manufacturing device according to the present invention as described above. In addition, the magnetic orientation can be achieved by forming a magnetic field perpendicular to the surface of the electrode sheet before the negative electrode slurry is discharged onto the electrode sheet.

[0097] In addition, the manufacturing method can control the spacing distance between the grooves of the groove mold set in the negative electrode manufacturing device (in other words, between the lips including the upper lip, the middle lip and the lower lip and the coating roller) according to the average thickness of the negative electrode slurry to be applied to the electrode sheet, thereby maintaining the crystal orientation of the carbon-based negative electrode active material. Even if the carbon-based negative electrode active material is oriented before discharge so that a specific crystal plane has a predetermined angle relative to the surface of the electrode sheet, the angle or degree of orientation can also be changed according to the fluid movement at the angle at which the negative electrode slurry is applied to the surface of the electrode sheet before discharge. Therefore, according to the present invention, the average thickness of the negative electrode slurry applied to the electrode sheet can be adjusted to be greater than the separation distance between the lip of the groove mold and the coating roller set in the negative electrode manufacturing equipment, so as to minimize the fluid movement according to the angle at which the negative electrode slurry is applied. For example, the average thickness of the negative electrode slurry applied to the electrode sheet can be adjusted to 1.01 to 2.00 times; 1.01 to 1.80 times; 1.01 to 1.50 times; 1.1 to 1.5 times; or 1.2 to 1.9 times the spacing distance between the lip of the groove mold and the coating roller set in the negative electrode manufacturing device.

[0098] In addition, applying the negative electrode slurry to which magnetism is applied to the electrode sheet can be performed on the electrode sheet conveyed at a predetermined speed. The conveying speed can be the same as the speed at which the negative electrode slurry is applied to the electrode sheet. For example, applying the negative electrode slurry to the electrode sheet can be performed at a speed of 5m / min to 100m / min, and more specifically, can be performed at the following speeds: 5m / min to 35m / min; 10m / min to 35m / min; 20m / min to 35m / min; 10m / min to 30m / min; 5m / min to 20m / min; 5m / min to 25m / min; or 15m / min to 25m / min.

[0099] By applying the negative electrode slurry within the above speed range, the present invention can prevent the negative electrode slurry from being uniformly applied on the surface of the electrode sheet due to a significantly slower application speed. At the same time, it can prevent the process efficiency and productivity from being reduced; and it can prevent the crystal orientation state of the carbon-based negative electrode active material present in the negative electrode slurry from being destroyed due to an excessively high speed, resulting in a reduction in the degree of orientation.

[0100] In addition, the method of manufacturing a negative electrode for a secondary battery according to the present invention may further include applying the negative electrode slurry to which magnetism is applied to an electrode sheet, and then drying the applied negative electrode slurry to form a negative electrode active layer.

[0101] Forming the negative electrode active layer refers to the process of fixing the carbon-based negative electrode active material contained in the negative electrode slurry to the electrode sheet by drying the negative electrode slurry. This step can be applied in any manner without limitation, as long as the carbon-based negative electrode active material in the negative electrode slurry applied to the electrode sheet can be fixed and the degree of orientation thereof relative to the surface of the electrode sheet is minimized.

[0102] Specifically, drying can be applied by applying energy such as light, wavelength, heat, etc., and drying can be performed using an ultraviolet dryer, a near-infrared dryer, a far-infrared dryer, a hot air dryer, a vacuum oven, etc. alone or in combination.

[0103] Meanwhile, the carbon-based negative electrode active material contained in the negative electrode slurry may include a carbon-based negative electrode active material conventionally applied in a lithium secondary battery. Specifically, the carbon-based negative electrode active material refers to a material with carbon atoms as the main component. Such carbon-based negative electrode active materials may include graphite. Graphite may include one or more of natural graphite and artificial graphite, but preferably natural graphite, or a mixture of natural graphite and artificial graphite.

[0104] Preferably, the carbon-based negative electrode active material is a spherical graphite assembly formed by a plurality of flake graphites. Flake graphite may include natural graphite, artificial graphite, calcined carbon (blocky mesophase) based on tar and pitch, graphitized coke (raw coke, green coke, pitch coke, needle coke, petroleum coke, etc.), etc., and is preferably assembled using a variety of highly crystalline natural graphites. In addition, a graphite assembly can be formed by assembling 2 to 100 sheets (preferably 3 to 20 sheets) of flake graphite.

[0105] This carbon-based negative electrode active material (specifically, graphite) may have a spherical particle shape, wherein the sphericity of the graphite particles may be greater than or equal to 0.75, such as 0.75 to 1.0; 0.75 to 0.95; 0.8 to 0.95; or 0.90 to 0.99. Here, "sphericity" may refer to the ratio of the shortest diameter (short diameter) to the longest diameter (long diameter) in any diameter passing through the center of the particle, where a sphericity of 1 indicates that the particle has a spherical shape. Sphericity can be measured by a particle shape analyzer. The present invention can achieve high conductivity of the negative electrode active layer by making the shape of the carbon-based negative electrode active material close to a spherical shape, thereby increasing the capacity of the battery. The present invention also has the advantage that the specific surface area of ​​the negative electrode active material can be increased, and thus the adhesion between the negative electrode active layer and the current collector can be improved.

[0106] In addition, the carbon-based negative active material may exhibit an average particle size (D50) of 0.5 μm to 10 μm, and more specifically, may exhibit an average particle size (D50) of 2 μm to 7 μm; 0.5 μm to 5 μm; or 1 μm to 3 μm.

[0107] The average particle size of spherical natural graphite may be advantageous to have a smaller particle size to maximize the disorder of each particle in the expansion direction, thereby preventing the particles from expanding during lithium ion charging. However, when the particle size of natural graphite is less than 0.5 μm, due to the increase in the number of particles per unit volume, a large amount of binder is required, and the sphericity and sphericity transfer coefficient will be low. On the other hand, when the maximum particle size exceeds 10 μm, the expansion becomes severe, and with repeated charge and discharge, the binding properties between particles and the binding properties of particles to the current collector are reduced, which significantly reduces the cycle characteristics.

[0108] Furthermore, the negative electrode slurry may further include a conductive material, a binder, a thickener, etc. in addition to the carbon-based negative electrode active material, and these negative electrode slurries may be applied as conventionally used in the art.

[0109] The conductive material may include one or more of carbon black, acetylene black, Ketjen black, carbon nanotubes, carbon fibers, etc., but is not limited thereto.

[0110] As an example, the negative electrode active layer may contain carbon black, carbon nanotubes, carbon fibers, etc., alone or in combination as conductive materials.

[0111] In this case, the content of the conductive material may be 0.1 to 10 parts by weight, more specifically 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, 2 to 6 parts by weight, or 0.5 to 2 parts by weight, relative to a total of 100 parts by weight of the negative electrode active layer. The present invention can control the content of the conductive material within the range as described above, thereby preventing the increase in the resistance of the negative electrode due to the low content of the conductive material, thereby reducing the charging capacity. In addition, the problem of a reduction in the charging capacity due to a reduction in the content of the negative electrode active material caused by an excessive amount of the conductive material can be prevented, or the problem of a reduction in the fast charging characteristics due to an increase in the loading amount of the negative electrode active layer can be prevented.

[0112] In addition, the binder can be appropriately applied as a component to facilitate the bonding of the negative electrode active material to the conductive material and the negative electrode current collector without reducing the electrical properties of the electrode, but more specifically, the binder can apply any one or more of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVdF), polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber and fluorinated rubber.

[0113] Based on 100 parts by weight of the negative electrode slurry in total, the content of the binder may be 0.1 to 10 parts by weight, more specifically 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, or 2 to 6 parts by weight. The present invention can control the content of the binder contained in the negative electrode slurry within the above range, thereby preventing the adhesion of the negative electrode active layer from being deteriorated due to low binder content, or preventing the electrical properties of the electrode from being deteriorated due to excessive binder.

[0114] The method of manufacturing a negative electrode sheet for a secondary battery according to the present invention is advantageous in having the above-mentioned composition, which enables the carbon-based negative electrode active material of the negative electrode slurry applied on the current collector to be uniformly aligned with a high degree of orientation.

[0115] Secondary battery negative electrode

[0116] In addition, in one embodiment, the present invention provides,

[0117] A secondary battery negative electrode prepared by the above method.

[0118] The negative electrode for a lithium secondary battery according to the present invention includes a negative electrode active layer on at least one side of a current collector, the negative electrode active layer including a carbon-based negative electrode active material as a main component. The negative electrode active layer refers to a layer that is electrically active as a negative electrode. The negative electrode active layer is prepared by applying an electrode slurry including a carbon-based negative electrode active material to both sides of the current collector, followed by drying and pressing, wherein the carbon-based negative electrode active material performs an electrochemical redox reaction during the charge and discharge of the secondary battery. Here, the negative electrode active layer is formed by applying a magnetic negative electrode slurry to an electrode sheet using the above-mentioned negative electrode manufacturing device and drying, wherein the main component (carbon-based negative electrode active material) is characterized by a high degree of crystal orientation relative to the surface of the electrode sheet, thereby having high energy density and charge / discharge performance.

[0119] Specifically, the negative electrode according to the present invention can be aligned so that the carbon-based negative electrode active material contained in the negative electrode active layer has a predetermined angle relative to the electrode sheet (or negative electrode current collector). This alignment of the carbon-based negative electrode active material can be used to reduce the degree of disorder in the negative electrode active layer, thereby reducing the electrode resistance and providing a mobile path for lithium ions. At this time, the crystal orientation of the carbon-based negative electrode active material (e.g., graphite) can be determined by crystallization analysis of the carbon-based negative electrode active material contained in the negative electrode active layer.

[0120] In one embodiment, the negative electrode active layer may align the carbon-based negative electrode active material in a specific direction relative to the current collector, so that the X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer satisfies an average alignment degree of 0.9 or less of the carbon-based negative electrode active material, as expressed in the following equation 2:

[0121] [Equation 2]

[0122] OI=I 004 / I 110

[0123] In equation 2,

[0124] I 004 It refers to the area of ​​the peak representing the [0,0,4] crystal plane in the X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer.

[0125] I 110 Refers to the area of ​​the peak representing the [1,1,0] crystal plane in X-ray diffraction spectrum (XRD) measurement of the silver negative electrode active layer.

[0126] The above equation 2 can be an indicator of the degree of alignment of the crystal structure of the spherical carbon-based negative electrode active material in a specific direction (specifically, relative to the surface of the negative electrode current collector) during X-ray diffraction measurement. More specifically, the negative electrode active layer can be aligned with the peaks at 2θ=26.5±02°, 42.4±02°, 43.4±0.2°, 44.6±0.2°, 54.7±0.2° and 77.5±0.2°, respectively, representing the [0,0,2] plane, [1,0,0] plane, [1,0,1]R plane, [1,0,1]H plane, [0,0,4] plane and [1,1,0] plane of the carbon-based negative electrode active material (graphite). Moreover, the peak appearing at 2θ=43.4±0.2° can be regarded as an overlap of the peaks corresponding to the [1,0,1]R plane of the carbon-based negative electrode active material and the [1,1,1] plane of the current collector (such as copper (Cu)).

[0127] Among them, the alignment degree (OI) of the carbon-based negative active material can be measured by the ratio of the area of ​​the peak at 2θ=77.5±0.2° representing the [1,1,0] plane to the area of ​​the peak at 2θ=54.7±0.2° representing the [0,0,4] plane, specifically, the ratio of the area obtained by integrating the intensity of the peak. Here, since the peak at 2θ=54.7±0.2° is a peak of the [0,0,4] plane having an inclination with the negative current collector in the crystal plane of graphite, the alignment degree (OI) may refer to a value close to 0, the inclination relative to the surface of the negative current collector is close to 90°, and when the value is large, the inclination relative to the surface of the negative current collector is close to 0° or 180°. In this regard, the negative electrode active layer according to the present invention can have a carbon-based negative electrode active material with a lower degree of alignment (OI) compared to the case where the carbon-based negative electrode active material is not self-aligned, because the carbon-based negative electrode active material is aligned so that the carbon-based negative electrode active material has an angle close to perpendicular to the negative electrode current collector, such as 60° or greater, 70° or greater, 70° to 90°, 80° to 90°, 65° to 85°, or 70° to 85° relative to the negative electrode current collector.

[0128] When measured by X-ray diffraction relative to the surface of the negative electrode active layer, the alignment index (OI) of Equation 2 of the negative electrode according to the present invention is 0.9 or less, more specifically, it can be 0.8 or less; 0.7 or less; 0.6 or less; 0.1 to 0.9; 0.2 to 0.8; 0.3 to 0.7; 0.2 to 0.6; or 0.4 to 0.6.

[0129] Meanwhile, the average thickness of the negative electrode active layer may be 50 μm to 300 μm, more specifically 50 μm to 250 μm; 100 μm to 250 μm; or 100 μm to 200 μm. The present invention can not only improve the energy density of the electrode by adjusting the average thickness of the negative electrode active layer to the above range, but also uniformly control the disorder of the carbon-based negative electrode active material contained in the negative electrode active layer.

[0130] In addition, the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, copper, stainless steel, nickel, titanium, calcined carbon, etc. can be used as the negative electrode current collector, and in the case of copper or stainless steel, surface treatments of carbon, nickel, titanium, silver, etc. can also be used. In addition, considering the conductivity and total thickness of the negative electrode to be manufactured, the average thickness of the negative electrode current collector can be appropriately applied to 1 μm to 500 μm.

[0131] Hereinafter, the present invention will be described in more detail with the aid of Examples and Experimental Examples.

[0132] However, the following embodiments and experimental examples are merely illustrative of the present invention, and the present invention is not limited to the following embodiments and experimental examples.

[0133] Examples 1 to 5 and Comparative Examples 1 to 2. Production of secondary battery negative electrode sheet

[0134] First, natural graphite and artificial graphite were prepared as carbon-based negative electrode active materials (average particle size: 4±1 μm, sphericity: 0.94±0.2), and a first negative electrode slurry and a second negative electrode slurry were prepared using the prepared carbon-based active materials.

[0135] Specifically, the first negative electrode slurry was prepared by mixing natural graphite and artificial graphite in a weight ratio of 2:8 to prepare a negative electrode active material, using carbon black as a conductive material, and using carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) as binders. The first negative electrode slurry was prepared by mixing 95 parts by weight of mixed graphite, 1 part by weight of carbon black, 1.5 parts by weight of carboxymethyl cellulose (CMC) and 2.5 parts by weight of styrene butadiene rubber (SBR) with water to 50% solid.

[0136] In addition, the second negative electrode slurry was prepared by the same method as the first negative electrode slurry, but only artificial graphite was used as the carbon-based negative electrode active material. In addition, the viscosity of the prepared first negative electrode slurry and the second negative electrode slurry was adjusted to 6300±200 cps at 25°C.

[0137] Separately, a negative electrode manufacturing device was prepared, the negative electrode manufacturing device including: a double-groove mold having a first groove and a second groove, wherein an upper block, a first spacer, an intermediate block, a second spacer, and a lower block are sequentially stacked to provide a first groove and a second groove, in which a negative electrode slurry can be discharged at the front end; and a coating roller, which is arranged to face the groove of the groove mold. At this time, the following aspects of the negative electrode manufacturing device are adjusted as shown in Table 1 below: i) the polarity type of magnetism given to the upper lip of the upper block, the middle lip of the intermediate block, and the lower lip of the lower block; ii) the magnetic field strength applied to the lip including the upper lip, the middle lip, and the lower lip; and iii) the ratio (G / M) of the magnetic field strength (G) applied to the lip to the moving speed (M) of the copper thin plate (in other words, the electrode sheet).

[0138] The previously prepared negative electrode slurry was injected into the prepared negative electrode manufacturing device, and the negative electrode slurry was applied to the surface of a copper thin plate (thickness: 8 μm) conveyed at a speed (M) of 50 m / min. Then, hot air was continuously applied to the applied negative electrode slurry to dry it to form a negative electrode active layer.

[0139] [Table 1]

[0140] upper lip Middle lip lower lip Coating roller Magnetic field strength at lips [G] <![CDATA[G lip / G roll ]]> Example 1 N pole N pole N pole S pole 100 0.03 Example 2 N pole N pole N pole S pole 1500 0.5 Example 3 N pole N pole N pole S pole 3300 1.1 Example 4 N pole N pole N pole S pole 1500 0.1 Example 5 N pole N pole N pole S pole 1500 1.5 Comparative Example 1 - - - - - - Comparative Example 2 N pole S pole N pole S pole 1500 0.5 Comparative Example 3 N pole N pole N pole N pole 1500 0.5

[0141] Experimental example

[0142] The orientation exhibited by the carbon-based negative electrode active material of the negative electrode of the secondary battery manufactured using the negative electrode manufacturing apparatus according to the present invention was evaluated.

[0143] Specifically, X-ray diffraction spectra (XRD) were performed on any three points of the negative electrode active layer of each negative electrode prepared in Examples 1 to 5 and Comparative Examples 1 to 2, and the spectra were measured. The measurement conditions of X-ray diffraction (XRD) were as follows:

[0144] -Target: Cu (Kα-ray) graphite monochromator

[0145] - Slits: Transmitting slit = 1 degree, Receiving slit = 0.1 mm, Scattering slit = 1 degree

[0146] -Measurement cross section: [1,1,0] plane: 76.5°<2θ<78.5° / [0,0,4] plane: 53.5°<2θ<56.0°.

[0147] According to the spectrum measured under the above conditions, the alignment degree (OI) of each carbon-based negative electrode active material was calculated according to Equation 2, and the average alignment degree was obtained according to the calculated alignment degrees (OI) of the carbon-based negative electrode active material at 3 points. The results are shown in Table 2.

[0148] [Equation 2]

[0149] OI=I 004 / I 110

[0150] In equation 2,

[0151] I 004 It refers to the area of ​​the peak representing the [0,0,4] crystal plane in the X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer.

[0152] I 110 Refers to the area of ​​the peak indicating the [1,1,0] crystal plane in X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer.

[0153] [Table 2]

[0154] Average alignment Example 1 1.03 Example 2 0.45 Example 3 0.81 Example 4 0.65 Example 5 0.59 Comparative Example 1 5.24 Comparative Example 2 5.83 Comparative Example 3 6.41

[0155] As shown in Table 2 above, it can be seen that the negative electrode manufactured using the negative electrode manufacturing apparatus according to the present invention has a higher degree of orientation of the carbon-based negative electrode active material contained in the negative electrode active layer.

[0156] This means that when the front ends of the upper block, the middle block and the lower block (in other words, each lip) of the double-grooved mold are magnetized with the same polarity when the negative electrode slurry is discharged, and then the negative electrode slurry is applied to the electrode sheet (or negative electrode collector) at a predetermined speed, before the negative electrode slurry is discharged, the carbon-based negative electrode active material is oriented nearly vertically relative to the crystal plane of the electrode sheet, and the carbon-based negative electrode active material is applied and maintained on the electrode sheet in this orientation induced state to form a negative electrode active layer.

[0157] Judging from these results, the negative electrode manufacturing device according to the present invention has the advantage that the carbon-based negative electrode active material in the discharged negative electrode slurry can be applied in a state where the carbon-based negative electrode active material is oriented at a predetermined angle relative to the surface of the current collector. Therefore, the carbon-based negative electrode active material of the manufactured negative electrode not only has an excellent orientation degree, but also has the advantage of being easy to apply to mass production processes.

[0158] As described above, the present invention has been described in more detail with the aid of the accompanying drawings and embodiments. However, since the configuration described in the accompanying drawings or embodiments described herein is only one embodiment of the present invention and does not represent the overall technical concept of the present invention, it should be understood that the present invention covers various equivalent examples, variants, and alternative examples when the present application is proposed.

[0159] Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be defined by the claims of the patent.

[0160] [Explanation of Reference Numerals]

[0161] 10: Negative electrode manufacturing device for secondary battery according to the present invention

[0162] 100: Double groove mold 110: Upper mold

[0163] 111: Upper lip 112: Upper body

[0164] 120: Middle mold 121: Middle lip

[0165] 122: middle body 130: lower mold

[0166] 130a: opening 140: discharge slot

[0167] 200: coating roller 210: coating roller magnet

[0168] 300: Electrode sheet

[0169] A: Unoriented segment B: Oriented segment

[0170] I: Body II: Lip

[0171] III: Coating Area

[0172] MD: Magnetic field direction CM: Carbon-based negative electrode active material

Claims

1. A negative electrode manufacturing device for a secondary battery, the negative electrode manufacturing device for a secondary battery is used to apply a negative electrode slurry containing a carbon-based negative electrode active material on an electrode sheet, the negative electrode manufacturing device for a secondary battery comprises: A double-groove mold, the double-groove mold comprising an upper block, a middle block, and a lower block, and a first groove and a second groove, the first groove being configured to pass through a gap between the upper block and the middle block and discharge a first negative electrode slurry, and the second groove being configured to pass through a gap between the middle block and the lower block and discharge a second negative electrode slurry; as well as a coating roller that is opposite to the first groove and the second groove of the double groove mold and conveys the electrode sheet coated with the negative electrode slurry discharged from each groove, wherein the upper block, the middle block and the lower block include an upper lip, a middle lip and a lower lip forming an outlet at their respective front ends, and the upper lip, the middle lip and the lower lip exhibit magnetic properties of the same polarity, and The coating roller exhibits a magnetic polarity opposite to that of the upper lip.

2. The negative electrode manufacturing device for a secondary battery according to claim 1, wherein: When the negative electrode slurry is discharged, a magnetic field with a strength of 500G to 3000G is applied to the upper lip, the middle lip, and the lower lip.

3. The negative electrode manufacturing device for a secondary battery according to claim 1, wherein: The double slot die satisfies the following equation 1: [Equation 1] G lip / G roll ≤1 In equation 1, G lip refers to the magnetic field strength (in G) applied to the upper lip, the middle lip and the lower lip, G roll refers to the magnetic field strength (in G) applied to the coating roller.

4. The negative electrode manufacturing device for a secondary battery according to claim 1, wherein: The upper lip, the middle lip, and the lower lip have a structure including at least one of a permanent magnet and an electromagnet.

5. The negative electrode manufacturing device for a secondary battery according to claim 1, wherein: The negative electrode manufacturing device for a secondary battery further includes a drying section for drying the negative electrode slurry applied to the electrode sheet, and The drying part is provided at a position such that the negative electrode slurry discharged from the double-grooved mold can reach the electrode sheet within 20 seconds from the time when the negative electrode slurry is applied.

6. A method for manufacturing a negative electrode for a secondary battery, the method for manufacturing a negative electrode for a secondary battery comprising the following steps: Using the negative electrode manufacturing apparatus for a secondary battery according to claim 1, applying the negative electrode slurry to which magnetism is applied to an electrode sheet, Wherein, the negative electrode slurry contains carbon-based negative electrode active material.

7. The method for manufacturing a negative electrode for a secondary battery according to claim 6, wherein: An average thickness of the negative electrode slurry applied to the electrode sheet is greater than a separation distance between the grooves of the double groove mold and the coating roller provided in the negative electrode manufacturing apparatus for a secondary battery.

8. The method for manufacturing a negative electrode for a secondary battery according to claim 6, wherein: The negative electrode slurry applied to the electrode sheet has an average thickness of 100 μm or more.

9. The method for manufacturing a negative electrode for a secondary battery according to claim 6, wherein: Applying the negative electrode slurry to the electrode sheet is performed at a speed of 5 m / min to 100 m / min.

10. The method for manufacturing a negative electrode for a secondary battery according to claim 6, further comprising the following steps: After the negative electrode slurry is applied to the electrode sheet, the applied negative electrode slurry is dried to form a negative electrode active layer.

11. The method for manufacturing a negative electrode for a secondary battery according to claim 10, wherein: The alignment degree of the carbon-based negative electrode active material of the negative electrode active layer relative to the surface of the electrode sheet is 0.9 or less, as expressed by the following Equation 2: [Equation 2] OI=I 004 / I 110 In equation 2, I 004 It refers to the area of ​​the peak representing the [0,0,4] crystal plane in the X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer, I 110 It refers to the area of ​​the peak indicating the [1,1,0] crystal plane in X-ray diffraction spectrum (XRD) measurement of the negative electrode active layer.

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