Negative electrode manufacturing apparatus for secondary battery

Abstract

The present invention relates to an apparatus for manufacturing a negative electrode for a secondary battery and a method for manufacturing a negative electrode using the same. The negative electrode manufacturing device comprises an upper block, a middle block and a lower block, and a double-groove mold including a first groove and a second groove for discharging the negative electrode slurry through each gap between the upper block and the middle block and between the middle block and the lower block, in which an upper lip, a middle lip, and a lower lip are located at tips of the corresponding blocks, the upper lip and the lower lip are configured to apply magnetic fields of the same polarity, and the first groove and the second groove are configured to receive the negative electrode slurry. And the middle lip portion is configured to apply a magnetic field opposite to the upper lip in polarity. Therefore, the carbon-based negative electrode active material in the discharged negative electrode slurry can be applied, so that the crystal face is oriented to be approximately perpendicular to the surface of the negative electrode current collector. Therefore, the manufactured negative electrode has excellent directionality of the carbon-based negative electrode active material and has the advantage of being easily applied to a large-scale production process.

Description

Technical Field

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

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0173289 filed on December 13, 2022, the entire contents of which are incorporated herein by reference. Background Art

[0003] Recently, secondary batteries have been widely used not only in small devices such as portable electronic products but also in large and medium-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. Generally, the positive electrode includes 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, the 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 and artificial graphite. This graphite has a layered structure and is formed by stacking a plurality of layers in which carbon atoms form a network structure that unfolds in a planar shape. During charging, lithium ions can invade from the edges (layer overlap sides) of these graphite layers and diffuse between the layers, while during discharge, lithium ions can dissociate and release 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 transferring electrons is formed along the lateral direction of the layer.

[0006] In this regard, in lithium secondary batteries using graphite, a technology for magnetically orienting the graphite contained in the negative electrode to improve the charging performance of the negative electrode has been traditionally proposed. Specifically, it has the following structure: 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 roughly 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 dissociation of lithium ions can be smoothly implemented, 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] This orientation of graphite can be induced by coating a negative electrode slurry containing graphite on a current collector and applying a magnetic field to the undried negative electrode slurry. However, in the large-scale production of actual negative electrodes, it is difficult to ensure sufficient time to apply a magnetic field to induce graphite alignment of the negative electrode slurry, considering the production speed. 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 phenomenon of graphite being attracted by the magnetic field will occur at the end of the magnetic field, and the orientation of the graphite aligned perpendicular to the metal sheet will collapse, resulting in low orientation of graphite in the final manufactured negative electrode active layer.

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

[0009] [Related technical literature]

[0010] [Patent Document]

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

[0012] Technical issues

[0013] The present invention aims to provide a negative electrode manufacturing technology that can achieve a high degree of crystal orientation of a carbon-based negative electrode active material (such as graphite) contained in a negative electrode active layer while being suitable for large-scale production of negative electrodes for secondary batteries.

[0014] Technical Solution

[0015] In order to solve the above problems,

[0016] In one embodiment, the present invention provides,

[0017] A device for manufacturing an electrode sheet, on which a negative electrode slurry containing a carbon-based negative electrode active material is coated,

[0018] The negative electrode manufacturing device for a secondary battery comprises: a double-groove mold including an upper block, a middle block and a lower block, a first groove for discharging a first negative electrode slurry through a gap between the upper block and the middle block, and a second groove for discharging a second negative electrode slurry through a gap between the middle block and the lower block; and

[0019] a coating roller which 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] Among them, 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 each front end, and the upper lip, the middle lip and the lower lip exhibit magnetism of the same polarity, and the middle lip exhibits magnetism of opposite polarity to the upper lip to provide a negative electrode manufacturing device for a secondary battery.

[0021] 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 a strength of 500 G to 3,000 G can be applied when the negative electrode slurry is discharged.

[0022] In addition, the double-slot mold can satisfy the following formula 1:

[0023] [Formula 1]

[0024] 10≤G / M≤50

[0025] (In Formula 1,

[0026] G represents the strength of the magnetic field applied at the upper lip, middle lip and lower lip (unit: G),

[0027] M represents the speed at which the electrode sheet moves through the coating roller (unit: m / min).

[0028] In addition, the negative electrode manufacturing apparatus may further include a drying unit for drying the negative electrode slurry applied to the electrode sheet.

[0029] Furthermore, the drying part may be disposed at a position such that the negative electrode slurry discharged from the double tank mold can reach it within 20 seconds from the time when it is applied to the electrode sheet.

[0030] Furthermore, in one embodiment,

[0031] The present invention includes applying the negative electrode slurry to which a magnetic field is applied to an electrode sheet using the negative electrode manufacturing apparatus according to the present invention,

[0032] Provided is a method for manufacturing a negative plate for a secondary battery using a negative electrode slurry including a carbon-based negative electrode active material.

[0033] In this case, the average thickness of the negative electrode slurry applied to the electrode sheet may be greater than the separation distance between the groove 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.

[0034] 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.

[0035] The negative electrode slurry may have a viscosity of 2,000 cps to 15,000 cps at 25°C.

[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 negative electrode active layer may have an alignment degree of the carbon-based negative electrode active material with respect to the surface of the electrode sheet of 0.9 or less, represented by the following Formula 2:

[0038] [Formula 2]

[0039] OI=I 004 / I 110

[0040] In formula 2,

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

[0042] I 110 It represents the area of ​​the peak representing the [1,1,0] crystal plane in the X-ray diffraction spectrum (XRD) measurement result 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 be applied in a state where the crystal plane of the carbon-based negative electrode active material in the discharged negative electrode slurry is oriented to be nearly perpendicular to the surface of the current collector. Therefore, the manufactured negative electrode has the following advantages: not only has an excellent degree of orientation of the carbon-based negative electrode active material, but is also easy to apply to a large-scale production process. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0046] Figure 2 : is a perspective view illustrating 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 is a conceptual diagram illustrating a principle of coating a carbon-based negative electrode active material of a negative electrode slurry onto 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, and therefore, 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 substitutes within the spirit and technical scope of the present invention.

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

[0051] In addition, 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 a part is "directly" disposed "on" another part, but also a case where another part is interposed between them. Conversely, when a part of a layer, film, region, plate, etc. is disposed "under" another part, this includes not only a case where a part is "directly" disposed "under" another part, but also a case where another part is interposed between them. 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, "including as a main component" may mean including at least 50 wt.% (or at least 50 vol.%), at least 60 wt.% (or at least 60 vol.%), 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.%) of a defined component relative to the total weight (or total volume) of the negative electrode active material. For example, "including graphite as a main component of the negative electrode active material" may mean including 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.% of graphite based on the total weight of the negative electrode active material, and in some cases may mean that the entire negative electrode active material is graphite (including at least 100 wt.% of graphite).

[0053] In addition, in the present invention, the "lip portion" refers to an area including an upper lip of an upper block, a middle lip of a middle block, and a lower lip of a lower block. The lip portion may include a spacing space formed between a plurality of lips (i.e., an area where each lip is disposed in the first groove and the second groove).

[0054] Similarly, in the present invention, the "body portion" refers to a region including an upper body of an upper block, a middle body of an intermediate block, and a lower body of a lower block. The body portion may include a spacing space formed between the bodies (i.e., a region in which each body is disposed in the first groove and the second groove).

[0055] Hereinafter, the present invention will be described in more detail.

[0056] Negative electrode manufacturing device for secondary battery

[0057] In one embodiment, the present invention provides,

[0058] A device for manufacturing an electrode sheet, on which a negative electrode slurry containing a carbon-based negative electrode active material is coated, the negative electrode manufacturing device for a secondary battery comprising:

[0059] A double-groove mold, the double-groove mold comprising an upper block, a middle block and a lower block, a first groove and a second groove, the first groove being arranged through a gap between the upper block and the middle block and discharging a first negative electrode slurry, the second groove being arranged through a gap between the middle block and the lower block and discharging a second negative electrode slurry; and

[0060] a coating roller which 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,

[0061] 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 each front end, and the upper lip, the middle lip and the lower lip exhibit magnetism of the same polarity, while the middle lip exhibits magnetism of opposite polarity to the upper lip, so as to provide a negative electrode manufacturing device for a secondary battery.

[0062] The negative electrode manufacturing apparatus for a secondary battery according to the present invention is an apparatus applied to 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 onto a current collector.

[0063] Specifically, Figure 1 2 is a schematic cross-sectional view of the structure of a negative electrode manufacturing apparatus for a secondary battery according to the present invention. Figure 1 The negative electrode manufacturing device 10 includes a double-grooved 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, the same or different, can be double-coated on the current collector. Figure 2 As shown, the first groove 151 may be formed between the upper mold 110 and the middle mold 120 facing each other, and the second groove 152 may be formed between the middle mold 120 and the lower mold 130 facing each other.

[0065] For example, the double groove mold 100 may include a first spacer 141 and a second spacer 142 sequentially disposed between each of the upper mold 110, the middle mold 120, and the lower mold 120, so that a gap is provided between them to form a channel, in other words, a first groove 151 and a second groove 152 are formed, and the negative electrode slurry can be fluidly moved through the first groove 151 and the second groove 152. In this case, the upper height and the lower height of the groove can be determined by the thickness (in the Y-axis direction) of the first spacer 141 and / or the second spacer 142 that reflects the gap between each mold. The thickness of the first spacer 141 and / or the second spacer 142 can be controlled according to the purpose or capacity of the secondary battery.

[0066] Here, the thickness of each of the first spacer 141 and the second spacer 142 may independently be from 50 μm to 2,000 μm, and more specifically, from 50 μm to 1,500 μm; from 500 μm to 1,200 μm; from 800 μm to 1,200 μm; from 80 μm to 200 μm; from 200 μm to 500 μm; or from 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 placed in all areas except one of the respective opposing flange areas of the upper mold 110, the middle mold 120, and the lower mold 130. Therefore, a discharge groove (in other words, a first groove 151 and a second groove 152) through which the negative electrode slurry can be discharged to the outside is formed only between the front ends of the upper mold 110, the middle mold 120, and the lower mold 130. 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 first groove 151 and the second groove 152 are formed by the intervals between the corresponding lips 111, 121, and 131.

[0068] In addition, the first and second spacers 141 and 142 are preferably made of a material having a sealing property to prevent the negative electrode slurry from leaking into the gap between each of the upper mold 110, the middle mold 120, and the lower mold 130 except for the area where the first groove 151 and the second groove 152 are formed by acting as a gasket.

[0069] In addition, 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 located at their respective front ends, and an upper body 112, a middle body 122 and a lower body 132 extending from each lip and in close contact with the first separator 141 and / or the second separator 142 to form a channel through which the negative electrode slurry can move fluidly.

[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, and the middle lip 121 may exhibit magnetism having the opposite polarity to the upper lip 111. Therefore, a magnetic field may be formed in the first groove 151 and the second groove 152 formed by each of the lips 111, 121, and 131 in a direction perpendicular to the discharge direction of the negative electrode slurry.

[0071] like Figure 3 As shown, if the path of negative electrode slurry discharge and coating is divided into an unoriented section A and an oriented section B, the carbon-based negative electrode active material (CM, for example, graphite) of the negative electrode slurry is not affected by the magnetic field in the unoriented section A including the spacing between the main bodies 112, 122 and 132 of each mold (in other words, I: main body), and thus moves in a state with a high degree of freedom. However, in the oriented section B, the spacing between the upper lip 111, the middle lip 121 and the lower lip 131 showing the same polarity of magnetism (in other words, II: lip part) is included. In the lip part, the middle lip 121 showing the opposite polarity of magnetism to the upper lip 111 is interposed between the upper lip 111 and the lower lip 131 showing the same polarity of magnetism. Therefore, an attractive force can be applied between the lips 111, 121 and 131 to form a magnetic field direction (MD) perpendicular to the discharge direction of the negative electrode slurry. Therefore, before the negative electrode slurry is discharged to the negative electrode current collector, the carbon-based negative electrode active material (CM) contained in the negative electrode slurry (in other words, graphite) can be oriented so that the [0,0,2] crystal plane is roughly perpendicular to the negative electrode current collector. Once the negative electrode slurry is discharged, the graphite oriented in this way is switched so that its crystal orientation is perpendicular to the surface of the electrode sheet (or negative electrode current collector) along the flow direction (FD) of the negative electrode slurry itself. Since the graphite is coated on the negative electrode current collector (ie, corresponding to III: coating area), its crystal plane is switched to be perpendicular to the surface of the electrode sheet, so after the negative electrode slurry is coated, the graphite can have a high degree of orientation without any magnetic field application.

[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 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 than when 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, when the negative electrode slurry is discharged, the upper lip 111, the middle lip 121 and the lower lip 131 can be subjected to a magnetic field that meets the predetermined strength range. 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 the following strength: 500G to 3,000G (Gauss), or more specifically, 500G to 2,500G; 500G to 2,000G; 500G to 2,000G; 500G to 1,500G; 1,000G to 2,000G; 2,000G to 2,500G; 2,000G to 3,000G; 500G to 1,500G; or 500G to 900G.

[0074] The present invention can achieve a 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 present invention can adjust the crystal orientation of the carbon-based negative electrode active material to a direction close to perpendicular to the surface of the electrode sheet according to the fluid momentum and / or movement direction of the negative electrode slurry 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 that the separation distance between the lips is narrowed, and the discharge of the negative electrode slurry becomes difficult.

[0075] In addition, the double-grooved mold 100 can orient the crystal planes of the carbon-based negative electrode active material before discharging the negative electrode slurry so that they are close to parallel to the surface of the electrode sheet 300 or the negative electrode current collector; in the subsequent discharge of the negative electrode slurry, the fluid momentum and / or movement direction of the slurry can transform the crystal planes of the carbon-based negative electrode active material to be close to perpendicular to the surface of the electrode sheet 300 or the negative electrode current collector, and the fluid momentum and / or movement direction of the slurry can be controlled to meet the predetermined range of the ratio of the magnetic field intensity applied to each lip to the negative electrode slurry coating speed, or in other words, the speed at which the electrode sheet is moved by the coating roller 200, so that the carbon-based negative electrode active material with oriented crystal planes is coated on the electrode sheet 300 or the current collector while maintaining the orientation before discharge. More specifically, the double-grooved mold 100 can satisfy the following formula 1:

[0076] [Formula 1]

[0077] 10≤G / M≤50

[0078] In formula 1,

[0079] G represents the strength of the magnetic field applied at the upper lip, middle lip and lower lip (unit: G),

[0080] M represents the speed at which the electrode sheet moves through the coating roller (unit: m / min).

[0081] The orientation of the carbon-based negative electrode active material contained in the negative electrode slurry may be affected by the applied magnetic field strength, the separation distance of the magnets applying the magnetic field, the fluid momentum and / or the movement direction of the negative electrode slurry containing the carbon-based negative electrode active material, etc. Therefore, the present invention can select the ratio (G / M) of the magnetic field strength (G) applied to each lip to the speed (M) of the electrode sheet moving through the coating roller from 10 to 50 to satisfy Formula 1, so that the crystal plane of the carbon-based negative electrode active material of the negative electrode slurry applied to the electrode sheet can be oriented to be close to perpendicular to the surface of the electrode sheet 300. More specifically, the double-groove mold 100 can satisfy Formula 1 within the following ranges: 10 to 50 (i.e., 10≤G / M≤50); 10 to 40 (i.e., 10≤G / M≤40); 10 to 30 (i.e., 10≤G / M≤30); 10 to 20 (i.e., 10≤G / M≤20); 15 to 30 (i.e., 15≤G / M≤30); 25 to 50 (i.e., 25≤G / M≤50); 35 to 49 (i.e., 35≤G / M≤49); or 20 to 40 (i.e., 20≤G / M≤40).

[0082] In addition, the first groove 151 and the second groove 152 formed by the respective lips 111, 121 and 131 may be positioned so that the negative electrode slurry is discharged perpendicularly to the surface of the negative electrode collector. To this end, the double groove mold 100 may be positioned perpendicularly to the surface of the electrode sheet 300. Preferably, the double groove mold 100 may be provided with a coating roller 200 rotatably arranged facing the first groove 151 and the second groove 152 of the double groove mold 100, such as Figure 1 Therefore, the double groove mold 100 can apply the negative electrode slurry to the surface of the electrode sheet 300 or the negative electrode collector moving with the rotation of the coating roller 200.

[0083] In addition, the negative electrode manufacturing device 10 according to the present invention may also include a drying section (not shown) for drying the negative electrode slurry coated on the electrode sheet 300, wherein the drying section may be arranged at a position so that the negative electrode slurry discharged from the double-grooved mold 100 reaches the electrode sheet within 20 seconds from the time of coating on the electrode sheet, specifically 0.01 second to 20 seconds; 0.01 second to 15 seconds; 0.01 second to 10 seconds; or 0.01 second to 5 seconds.

[0084] 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 oriented carbon-based negative electrode active material inside the negative electrode slurry. To this end, the drying unit can be arranged at a position where the negative electrode slurry is dried before the crystal orientation of the carbon-based negative electrode active material applied to the surface of the electrode sheet 300 is reduced.

[0085] In addition, the drying part is formed by including a wall (not shown) blocking the periphery except for an inlet and an outlet for introducing and leading out the electrode sheet 300 to which the negative electrode slurry is applied, and a dryer (not shown) on the wall on the side where the electrode sheet 300 coated with the negative electrode slurry is led out for drying the electrode sheet.

[0086] When the electrode sheet 300 coated with the negative electrode slurry enters through the entrance of the drying part, it receives energy provided from the opposite wall, such as light, wavelength, heat, etc. 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 from occurring.

[0087] In addition, as long as the dryer can apply energy such as light, wavelength, heat, etc., and is conventionally used in the art, the dryer can be used without particular limitation. For example, the dryer can be used alone or in combination as an ultraviolet dryer, a near infrared dryer, a far infrared dryer, a hot air dryer, a vacuum oven, etc.

[0088] The negative electrode manufacturing device according to the present invention may have the above-mentioned structure, so that before the negative electrode slurry is discharged onto the negative electrode sheet, the crystal orientation of the carbon-based negative electrode active material is close to horizontal relative to the surface of the negative electrode current collector, and during the discharge of the negative electrode slurry, according to the fluid momentum and / or movement direction of the negative electrode current collector, the crystal orientation of the carbon-based negative electrode active material in the slurry is adjusted to be close to vertical relative to the surface of the negative electrode current collector. Therefore, the carbon-based negative electrode active material of the negative electrode manufactured using the above-mentioned negative electrode manufacturing device has an excellent crystal orientation relative to the negative electrode current collector. In addition, since there is no need to perform a separate orientation treatment on the carbon-based negative electrode active material after coating the negative electrode slurry, the negative electrode manufacturing does not require additional facilities and is easy to apply large-scale production processes.

[0089] Method for manufacturing negative electrode for secondary battery

[0090] In one embodiment, the present invention further provides,

[0091] According to the negative electrode manufacturing device of the present invention, it includes applying the negative electrode slurry to which the magnetic field is applied to the electrode sheet,

[0092] A method for manufacturing a negative electrode for a secondary battery is provided, wherein the negative electrode slurry includes a carbon-based negative electrode active material.

[0093] The manufacturing method of the 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 negative electrode slurry to which a magnetic field is applied 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 and the negative electrode slurry is applied to an electrode sheet (i.e., a current collector) at the same time. Therefore, the above-mentioned manufacturing method has the following advantages: after applying the negative electrode slurry, there is no need to separately perform crystal orientation of the carbon-based negative electrode active material, so the process is simple and economical, and it is easy to apply to large-scale production due to its excellent processability.

[0094] Here, the negative electrode slurry may include a carbon-based negative electrode active material magnetically oriented by the negative electrode manufacturing apparatus according to the present invention as described above. The magnetic orientation may be achieved by forming a magnetic field parallel to the surface of the electrode sheet.

[0095] In addition, the manufacturing method can control the spacing distance between the grooves of the groove mold arranged in the negative electrode manufacturing device (i.e., the lip part 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 coated, so that the crystal orientation of the carbon-based negative electrode active material is close to perpendicular to the electrode sheet (or negative electrode current collector).

[0096] In the oriented carbon-based negative electrode active material, once the negative electrode slurry is discharged, the orientation of the oriented crystal plane can change depending on the fluid movement direction of the negative electrode slurry. Therefore, the average thickness of the negative electrode slurry can be adjusted to be greater than the separation distance between the lip portion of the slot mold provided in the negative electrode manufacturing device and the coating roller, so that when the negative electrode slurry is discharged, the crystal plane orientation of the oriented carbon-based negative electrode active material can be changed by nearly 90°. 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 portion of the slot mold provided in the negative electrode manufacturing device and the coating roller. In addition, the average thickness of the negative electrode slurry applied to the electrode sheet can be greater than or equal to 100 μm. Specifically, the average thickness of the negative electrode slurry applied to the electrode sheet can be at least 100 μm but not more than 300 μm; at least 110 μm but not more than 190 μm; at least 200 μm but not more than 300 μm; at least 150 μm but not more than 230 μm; at least 100 μm but not more than 250 μm; or at least 100 μm but not more than 200 μm.

[0097] In addition, the fluid momentum of the negative electrode slurry during the discharge of the negative electrode slurry can affect the alignment of the carbon-based negative electrode active material. Therefore, before the negative electrode slurry is discharged, the viscosity of the negative electrode slurry can be adjusted to a predetermined range so that the crystal orientation of the predetermined carbon-based negative electrode active material can be easily controlled during the slurry coating process. Specifically, the negative electrode slurry can have the following viscosity at 25°C: 2000cps to 15000cps, and more specifically, 2000cps or more but less than 14,000cps; 2000cps or more but less than 12,000cps; 2000cps or more but less than 10,000cps; 5000cps or more but less than 15,000cps; 10,000cps or more but less than 15,000cps; 9000cps or more but less than 13,000cps; 11,000cps or more but less than 14,000cps; 2500cps or more but less than 6800cps; 2500cps or more but less than 6700cps; 3000cps or more but less than 6000cps; 3500cps or more but less than 6000cps; 3600cps or more but less than 5700cps; 4000cps or more but less than 6000cps; 5000cps or more but less than 6000cps; 4000cps or more but less than 5000cps; 3500cps or more but less than 4800cps; 5400cps or more but less than 6900cps; or 3500cps or more but less than 4900cps.

[0098] In addition, applying the negative electrode slurry to the electrode sheet to which the magnetic field is applied may be performed on the electrode sheet being conveyed at a predetermined speed. The conveying speed may be the same as the speed at which the negative electrode slurry is applied to the electrode sheet.

[0099] For example, the speed of coating the negative electrode slurry to the electrode sheet can be performed at a speed of 5m / min to 100m / min, more specifically, at the following speeds: 40m / min to 100m / min; 50m / min to 100m / min; 60m / min to 90m / min; 40m / min to 80m / min; 40m / min to 60m / min.

[0100] By performing the discharge of the coated negative electrode slurry within the speed range, the present invention can appropriately increase the fluid momentum of the negative electrode slurry when the negative electrode slurry is discharged. Therefore, the present invention can change the crystal orientation of the carbon-based negative electrode active material that is horizontal relative to the electrode sheet (or negative electrode current collector) before coating to be nearly vertical after coating. In addition, by performing the coating of the negative electrode slurry within the above-mentioned speed range, the present invention can prevent the uneven coating of the negative electrode slurry on the surface of the electrode sheet due to the significantly slower coating speed. At the same time, it is possible to prevent the processing efficiency and productivity from being reduced; and it is possible to prevent the crystal alignment state of the carbon-based negative electrode active material present in the negative electrode slurry from being destroyed due to excessively high speed, resulting in a reduced degree of orientation.

[0101] 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 the magnetic field is applied to the electrode sheet, and then drying the applied negative electrode slurry to form a negative electrode active layer.

[0102] 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 on the electrode sheet by drying the negative electrode slurry. This can be applied in any way 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 relative to the surface of the electrode sheet changes minimally.

[0103] Specifically, drying may be applied by applying energy such as light, wavelength, heat, etc., and drying may be performed by using an ultraviolet dryer, a near infrared dryer, a far infrared dryer, a hot air dryer, a vacuum oven, etc. alone or in combination.

[0104] Meanwhile, the carbon-based negative electrode active material contained in the negative electrode slurry may include a material conventionally coated as a carbon-based negative electrode active material in a lithium secondary battery. Specifically, a carbon-based negative electrode active material refers to a material having carbon atoms as a main component. Such a carbon-based negative electrode active material may include graphite. Graphite may include one or more of natural graphite and artificial graphite, but is preferably natural graphite, or a mixture of natural graphite and artificial graphite.

[0105] 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 preferably a plurality of highly crystalline natural graphites are gathered together. In addition, a graphite assembly may be formed by assembling 2 to 100, preferably 3 to 20 flake graphites.

[0106] This carbon-based negative electrode active material (specifically graphite) can have a spherical particle shape, wherein the sphericity of the graphite particles can 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" can refer to the ratio of the shortest diameter (short diameter) to the longest diameter (long diameter) among any diameters 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 realize a highly conductive negative electrode active layer by realizing the shape of the carbon-based negative electrode active material to be close to a spherical shape, thereby increasing the capacity of the battery. The present invention also has the following advantages: it can increase the specific surface area of ​​the negative electrode active material, thereby increasing the adhesion between the negative electrode active layer and the current collector.

[0107] In addition, the carbon-based negative electrode active material may exhibit an average particle size (D 50 ), and more specifically, can show the following average particle size (D 50 ): 2μm to 7μm; 0.5μm to 5μm; or 1μm to 3μm.

[0108] The average particle size of spherical natural graphite may advantageously have a smaller particle size so that the disorder of each particle in the expansion direction is maximized to prevent the particles from expanding during lithium ion charging. However, when the particle size of natural graphite is less than 0.5 μm, a large amount of binder is required due to the increase in the number of particles per unit volume, and the sphericity and sphericity transmission number may be low. On the other hand, when the maximum particle size exceeds 10 μm, the expansion becomes serious, and with repeated charge and discharge, the bonding properties between particles and the bonding properties of particles to the current collector are reduced, which can significantly reduce the cycle characteristics.

[0109] In addition, 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 may be applied according to those conventionally used in the art.

[0110] 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.

[0111] As another example, the negative electrode active layer may contain carbon black, carbon nanotubes, carbon fibers, etc. as the conductive material alone or in combination.

[0112] In this case, the content of the conductive material can 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 the total weight of the negative electrode active layer of 100 parts by weight. The present invention can control the content of the conductive material within the above range, thereby preventing the increase in the negative electrode resistance due to the low content of the conductive material, thereby reducing the charging capacity. In addition, it is also possible to prevent the problem of reduced charging capacity due to reduced content of negative electrode active materials caused by excessive conductive materials, or reduced fast charging characteristics due to increased loading of the negative electrode active layer.

[0113] In addition, a binder can be appropriately applied as a component that helps to bond 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 be applied to 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, including any one or more thereof.

[0114] Based on 100 parts by weight of the negative electrode slurry in total, the content of the binder may be from 0.1 to 10 parts by weight, more specifically, from 0.1 to 8 parts by weight, from 0.1 to 5 parts by weight, from 0.1 to 3 parts by weight, or from 2 to 6 parts by weight. The present invention can control the content of the binder contained in the negative electrode slurry to the above range, thereby preventing the adhesion of the negative electrode active layer from being deteriorated due to low binder content, or the electrical properties of the electrode from being deteriorated due to excessive binder.

[0115] The method of manufacturing a negative electrode sheet for a secondary battery according to the present invention has the following advantages: having the above-mentioned composition, it enables the carbon-based negative electrode active material of the negative electrode slurry coated on the current collector to be uniformly aligned with a high degree of orientation.

[0116] Secondary battery negative electrode

[0117] In addition, in one embodiment, the present invention provides,

[0118] A secondary battery negative electrode prepared by the above method.

[0119] The lithium negative electrode for a secondary battery according to the present invention includes a negative electrode active layer containing a carbon-based negative electrode active material as a main component on at least one side of a current collector. The negative electrode active layer refers to a layer that embodies the electroactivity of the negative electrode. The negative electrode active layer is prepared by coating an electrode slurry including a carbon-based negative electrode active material that electrochemically embodies an oxidation-reduction reaction during battery charging and discharging on both sides of the current collector, followed by drying and rolling.

[0120] Here, the negative electrode active layer is formed by applying the negative electrode slurry to which a magnetic field is applied to an electrode sheet using the above-mentioned negative electrode manufacturing apparatus and drying it, wherein the main component (carbon-based negative electrode active material) is characterized by having a high crystal orientation relative to the surface of the electrode sheet, thereby having high energy density and charge and discharge performance.

[0121] 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 movement 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 crystallographic analysis of the carbon-based negative electrode active material contained in the negative electrode active layer.

[0122] In one example, the negative electrode active layer may align the carbon-based negative electrode active material relative to the current collector in a certain direction so that the X-ray diffraction spectrum (XRD) measurement result of the negative electrode active layer satisfies the average alignment degree of the carbon-based negative electrode active material of 0.9 or less as expressed in Formula 2 below:

[0123] [Formula 2]

[0124] OI=I 004 / I 110

[0125] In formula 2,

[0126] I 004 It represents the area of ​​the peak representing the [0,0,4] crystal plane in the X-ray diffraction spectrum (XRD) measurement result of the negative electrode active layer,

[0127] I 110 It represents the area of ​​the peak representing the [1,1,0] crystal plane in the X-ray diffraction spectrum (XRD) measurement result of the negative electrode active layer.

[0128] Formula 2 above can be an indicator of the degree of alignment of the crystal structure of the spherical carbon-based negative electrode active material in a certain 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 peak of the carbon-based negative electrode active material (graphite) 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° 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, respectively. In addition, the peak appearing at 2θ=43.4±0.2° may be regarded as an overlap of peaks corresponding to the [1,0,1]R plane of the carbon-based negative active material and the [1,1,1] plane of the current collector such as copper (Cu).

[0129] Among them, the alignment degree (OI) of the carbon-based negative active material can be measured by the ratio of the peak area at 2θ = 77.5 ± 0.2° representing the [1, 1, 0] plane to the peak area at 2θ = 54.7 ± 0.2° representing the [0, 0, 4] plane, specifically, by the ratio of the areas obtained by integrating the peak intensities. Here, since the peak at 2θ = 54.7 ± 0.2° is a peak representing the [0, 0, 4] plane tilted with the negative current collector among the graphite crystal planes, the alignment degree (OI) may mean that when the value is close to 0, the inclination relative to the surface of the negative current collector is close to 90°, and when the value is larger, 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 low 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 an angle of more than 60°, more than 70°, 70-90°, 80-90°, 65-85° or 70-85° relative to the negative electrode current collector.

[0130] When the surface of the negative electrode active layer is measured by X-ray diffraction, the negative electrode according to the present invention can have an alignment index (OI) according to Formula 2 of 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.

[0131] In addition, the average thickness of the negative electrode active layer can be from 50 μm to 300 μm, more specifically, from 50 μm to 250 μm; from 100 μm to 250 μm; or from 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.

[0132] In addition, the negative electrode current collector is not particularly limited as long as it has high conductivity and does not cause 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, carbon, nickel, titanium, silver, etc. can also be used for surface treatment. 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 adopted from 1 μm to 500 μm.

[0133] Hereinafter, the present invention will be described in more detail through examples and experimental examples.

[0134] However, the following examples and experimental examples are merely illustrative of the present invention, and the present invention is not limited to the following examples and experimental examples.

[0135] Examples 1 to 5 and Comparative Examples 1 to 2. Preparation of Sheet for Secondary Battery Negative Electrode

[0136] 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.

[0137] 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, and using carbon black as a conductive material and carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) as a binder. 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.

[0138] 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.

[0139] In addition, a negative electrode manufacturing device was prepared, which includes: a double-groove mold having a first groove and a second groove, in which 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, wherein the negative electrode slurry can be discharged at the front end; and a coating roller arranged to face the groove of the groove mold. At this time, the negative electrode manufacturing device is adjusted as follows: i) the polarity type of the magnetism applied 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 portion 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 portion to the moving speed (M) of the copper thin plate (in other words, the electrode sheet) is adjusted, as shown in Table 1 below.

[0140] The negative electrode slurry prepared in advance 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.

[0141] [Table 1]

[0142]

[0143] Experimental example

[0144] The orientation exhibited by the carbon-based negative electrode active material for a negative electrode of a secondary battery manufactured using the negative electrode manufacturing apparatus according to the present invention was evaluated.

[0145] Specifically, for each negative electrode prepared in Examples 1 to 5 and Comparative Examples 1 to 2, an X-ray diffraction spectrum (XRD) of any three points of the negative electrode active layer was performed, and the spectrum was measured. The measurement conditions of X-ray diffraction (XRD) were as follows:

[0146] -Target: Cu (Kα-ray) graphite monochromator

[0147] - Slits: Transmitting slit = 1 degree, Receiving slit = 0.1 mm, Scattering slit = 1 degree

[0148] -Measurement section: [1,1,0] plane: 76.5 degrees < 2θ < 78.5 degrees / [0,0,4] plane: 53.5 degrees < 2θ < 56.0 degrees.

[0149] According to the spectrum measured under the above conditions, the alignment degree (OI) of each carbon-based negative electrode active material according to Formula 2 was calculated, and the average alignment degree was obtained from the calculated alignment degree (OI) of the carbon-based negative electrode active material at three points. The results are shown in Table 2.

[0150] [Formula 2]

[0151] OI=I 004 / I 110

[0152] In formula 2,

[0153] I 004 It represents the area of ​​the peak representing the [0,0,4] crystal plane in the X-ray diffraction spectrum (XRD) measurement result of the negative electrode active layer,

[0154] I 110 It represents the area of ​​the peak representing the [1,1,0] crystal plane in the X-ray diffraction spectrum (XRD) measurement result of the negative electrode active layer.

[0155] [Table 2]

[0156] Average alignment Example 1 1.17 Example 2 0.53 Example 3 0.78 Example 4 1.05 Example 5 2.12 Comparative Example 1 5.24 Comparative Example 2 5.81

[0157] 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 carbon-based negative electrode active material with a high degree of orientation contained in the negative electrode active layer.

[0158] This means that when magnetic fields of the same polarity are applied to the upper and lower lips constituting the double-groove mold and a magnetic field of opposite polarity is applied to the middle lip when discharging the negative electrode slurry, an attractive force is applied between these lips so that the crystal planes of the carbon-based negative electrode active material are oriented to be nearly horizontal relative to the surface of the electrode sheet (or negative electrode current collector), wherein the negative electrode slurry containing such carbon-based negative electrode active material is discharged onto the electrode sheet at a predetermined speed, causing the fluid momentum and direction of the negative electrode slurry to change the crystal orientation of the carbon-based negative electrode active material so that it is nearly vertical relative to the surface of the electrode sheet (or negative electrode current collector).

[0159] Judging from these results, the negative electrode manufacturing device according to the present invention has the following advantages: the carbon-based negative electrode active material in the discharged negative electrode slurry can be coated 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, so that the carbon-based negative electrode active material of the manufactured negative electrode not only has an excellent degree of orientation, but also has the advantage of being easy to apply to large-scale production processes.

[0160] As above, the present invention has been described in more detail through the drawings and embodiments. However, since the configuration described in the drawings or embodiments is only one embodiment of the present invention and does not represent the entire technical spirit of the present invention, it should be understood that the present invention covers various equivalents, modifications and substitutions at the time of filing this application.

[0161] 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 determined by the claims of the patent.

[0162] [Description of Reference Signs]

[0163] 10: Negative electrode manufacturing device for secondary battery according to the present invention

[0164] 100: Double-die coating machine 110: Upper die

[0165] 111: Upper lip 112: Upper body

[0166] 120: Middle mold 121: Middle lip

[0167] 122: middle body 130: lower mold

[0168] 131: lower lip 132: lower body

[0169] 130: Spacer

[0170] 141, 142: first spacer and second spacer

[0171] 141a, 142a: Open

[0172] 151, 152: First slot and second slot

[0173] 200: coating roller 300: electrode sheet

[0174] A: Unoriented segment B: Oriented segment

[0175] I: Main body II: Lip part

[0176] III: Coating area

[0177] MD: Magnetic field direction CM: Carbon-based negative electrode active material

Claims

1. A device for manufacturing an electrode sheet, on which a negative electrode slurry containing a carbon-based negative electrode active material is coated, A negative electrode manufacturing device for a secondary battery includes: A double-groove mold, the double-groove mold comprising an upper block, a middle block and a lower block, a first groove and a second groove, the first groove being arranged through a gap between the upper block and the middle block and discharging a first negative electrode slurry, the second groove being arranged through a gap between the middle block and the lower block and discharging a second negative electrode slurry; and a coating roller which 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 each front end, and the upper lip, the middle lip and the lower lip exhibit magnetism of the same polarity, and the middle lip exhibits magnetism of opposite polarity to 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, the upper lip, the middle lip, and the lower lip are applied with a magnetic field having an intensity of 500 G to 3,000 G.

3. The negative electrode manufacturing device for a secondary battery according to claim 1, wherein: The double-groove mold satisfies the following formula 1: [Formula 1] 10≤G / M≤50 In formula 1, G represents the intensity of the magnetic field applied at the upper lip, the middle lip and the lower lip, and the unit is G. M represents the speed at which the electrode sheet is moved by the coating roller, in m / min.

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 further includes a drying section for drying the negative electrode slurry applied to the electrode sheet. The drying part is provided at a position where 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 to the electrode sheet.

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: The negative electrode manufacturing apparatus according to claim 1 is used to apply the negative electrode slurry to which the magnetic field is applied to the electrode sheet, Wherein, the negative electrode slurry includes a carbon-based negative electrode active material.

7. The method for manufacturing a negative electrode for a secondary battery according to claim 6, wherein: The 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 provided in the negative electrode manufacturing apparatus and the coating roller.

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: The coating of the negative electrode slurry onto 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, wherein: The negative electrode slurry has a viscosity of 2,000 cps to 15,000 cps at 25°C.

11. 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.

12. The method for manufacturing a negative electrode for a secondary battery according to claim 11, wherein: The negative electrode active layer has an alignment degree of the carbon-based negative electrode active material with respect to the surface of the electrode sheet of 0.9 or less, represented by the following Formula 2: [Formula 2] OI=I 004 / I 110 In formula 2, I 004 represents the area of ​​the peak representing the [0,0,4] crystal plane in the X-ray diffraction spectrum (XRD) measurement result of the negative electrode active layer, I 110 It represents the area of ​​the peak representing the [1,1,0] crystal plane in the X-ray diffraction spectrum (XRD) measurement result of the negative electrode active layer.

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