KR20240038296A - Magnetic alignment device for negative electrode and method for manufacturing using the same - Google Patents

Abstract

The present invention relates to a magnetic alignment device for a negative electrode and a method of manufacturing a negative electrode using the same. The magnetic alignment device applies a magnetic field by introducing magnet parts to the upper and lower parts of the negative electrode current collector to which the negative electrode slurry is applied, and By transporting the negative electrode current collector so that the separation distance between the magnet part introduced at the bottom and the negative electrode current collector has a predetermined inclination while passing through the magnet part, the attraction phenomenon of the carbon-based negative electrode active material due to the magnetic force generated at the end of the magnet part can be reduced. Therefore, there is an advantage of being able to manufacture a negative electrode with a significantly high degree of alignment of the carbon-based negative electrode active material contained in the negative electrode slurry.

Description

Magnetic alignment device for cathode and method of manufacturing cathode using same {MAGNETIC ALIGNMENT DEVICE FOR NEGATIVE ELECTRODE AND METHOD FOR MANUFACTURING USING THE SAME}

The present invention relates to a magnetic alignment device that can align the carbon-based negative electrode active material contained in the negative electrode active layer to a high level when manufacturing a negative electrode, and a method of manufacturing a negative electrode using the same.

Recently, secondary batteries have been widely applied not only to small devices such as portable electronic devices, but also to medium-to-large devices such as battery packs of hybrid vehicles or electric vehicles or power storage devices.

These secondary batteries are power generation devices capable of charging and discharging with a stacked structure of anode/separator/cathode. Generally, the positive electrode contains lithium metal oxide as a positive electrode active material, and the negative electrode contains a carbon-based negative electrode active material such as graphite, so when charging, Lithium ions released from the positive electrode are inserted into the carbon-based negative electrode active material of the negative electrode, and during discharging, lithium ions contained within the carbon-based negative electrode active material are inserted into the lithium metal oxide of the positive electrode, and charging and discharging are repeated.

At this time, the negative electrode active material used in the negative electrode includes graphite materials such as natural graphite. This kind of graphite has a layered structure and is formed by stacking multiple layers in which carbon atoms form a network structure and spread out in a planar shape. During charging, lithium ions invade the edge surface of these graphite layers (the surface where the layers overlap) and diffuse between layers. Additionally, during discharge, lithium ions may desorb and be released from the edge of the layer. In addition, since the electrical resistivity of graphite in the plane direction of the layer is lower than that in the stacking direction of the layers, a conduction path for electrons bypassed along the plane direction of the layer is formed.

In this regard, in a conventional lithium secondary battery using graphite, a technology has been proposed to orient the graphite contained in the negative electrode by a magnetic field in order to improve the charging performance of the negative electrode. Specifically, when forming the cathode, the [0,0,2] crystal plane of graphite is oriented in a magnetic field so that it is almost horizontal with respect to the cathode current collector, and this is fixed. In this case, since the edge surface of the graphite layer faces the positive electrode active layer, the insertion and desorption of lithium ions is performed smoothly, and the electronic conduction path is shortened, thereby improving the electronic conductivity of the negative electrode, thereby improving the charging performance of the battery. can do.

For this purpose, when manufacturing a negative electrode, a method of aligning graphite by applying a magnetic field to a negative electrode slurry containing graphite as a carbon-based negative electrode active material using a magnetic alignment device as shown in FIG. 1 is applied. However, this method applies a magnetic field by placing permanent magnets on the top and bottom of a thin metal plate coated with cathode slurry, and it is difficult to maintain a constant magnetic force and the ease of operation is low. In addition, in this method, an attraction phenomenon due to magnetic force occurs at the end of the permanent magnet, that is, the end of the magnetic field, and the graphite aligned perpendicularly to the metal sheet collapses, so the graphite in the finally manufactured cathode active layer is not aligned. There is a lower limit.

Republic of Korea Patent Publication No. 10-2018-0048131 Republic of Korea Patent Publication No. 10-2022-0060017

The purpose of the present invention is to control the distance between the magnet part used to apply a magnetic field when manufacturing a negative electrode and the negative electrode slurry located on the surface of the negative electrode current collector, so that the carbon-based negative electrode active material contained in the negative electrode slurry exhibits a high degree of alignment even if it escapes the magnetic field. The aim is to provide a magnetic alignment device for a cathode and a method of manufacturing a cathode using the same.

In order to solve the above-mentioned problems,

In one embodiment, the present invention

A transfer unit that transfers the negative electrode current collector coated with the negative electrode slurry containing a carbon-based negative electrode active material in one direction; and

It includes a first magnet portion and a second magnet portion spaced apart from each other on the upper and lower portions of the conveyed negative electrode current collector,

The transfer unit transfers the negative electrode current collector so that it is adjacent to the second magnet unit based on the point where the separation distance between the first magnet unit and the second magnet unit is 1/2, and the transferred negative electrode current collector is relative to the second magnet unit. A magnetic alignment device for cathodes that are transferred to have a predetermined inclination is provided.

Here, the negative electrode current collector may be transferred so that the separation distance from the second magnet unit increases as it is transferred from the inlet through which the first and second magnet units are introduced to the outlet where it is discharged.

Specifically, the separation distance between the negative electrode current collector and the second magnet portion is shorter than 1/2 of the separation distance between the first magnet portion and the second magnet portion and can satisfy the following equation 1:

[Equation 1]

D _en ≤0.99D _ex

In equation 1,

D _en represents the separation distance between the negative electrode current collector and the second magnet portion at the inlet where the negative electrode current collector is introduced into the first magnet portion and the second magnet portion,

D _ex represents the separation distance between the negative electrode current collector and the second magnet portion at the outlet where the negative electrode current collector is discharged from the first magnet portion and the second magnet portion.

In addition, the transfer unit includes a first transfer device and a second transfer device at the inlet through which the negative electrode current collector is introduced into the first magnet portion and the second magnet portion and the outlet through which the negative electrode current collector is discharged, respectively, and the first transfer device is connected to the second magnet. It may include a tilt control device that controls the separation distance between the negative electrode current collector and the second magnet portion, which is transported by performing an upward and downward movement in the vertical direction with respect to the portion.

In addition, the first magnet portion and the second magnet portion may include magnets having opposite poles, and the separation distance between the first magnet portion and the second magnet portion may be 10 mm to 50 mm.

Furthermore, the magnetic alignment device may further include a drying unit that dries the negative electrode slurry in which the carbon-based negative electrode active material is aligned by the first magnet unit and the second magnet unit.

In addition, in one embodiment of the present invention,

Applying a negative electrode slurry containing a carbon-based negative electrode active material on the negative electrode current collector;

Aligning the carbon-based negative electrode active material contained in the negative electrode slurry using the magnetic alignment device according to the present invention described above; and

Provided is a method of manufacturing a negative electrode including the step of drying a negative electrode slurry in which carbon-based negative electrode active materials are aligned to form a negative electrode active layer.

At this time, the carbon-based negative active material may include one or more types of natural graphite and artificial graphite.

In addition, the manufactured negative electrode active layer may have an alignment degree of 0.1 to 0.6 of the carbon-based negative electrode active material represented by the following equation 2:

[Equation 2]

OI = I ₀₀₄ /I ₁₁₀

In equation 2,

I ₀₀₄ represents the area of the peak representing the [0,0,4] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer,

I ₁₁₀ represents the area of the peak representing the [1,1,0] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer.

The magnetic alignment device according to the present invention applies a magnetic field by introducing a magnet portion to the upper and lower portions of the negative electrode current collector to which the negative electrode slurry is applied, and while the negative electrode current collector passes through the magnet portion, the magnet portion introduced to the lower portion and the negative electrode current collector By transporting the negative electrode current collector so that the separation distance has a predetermined inclination, the attraction phenomenon of the carbon-based negative electrode active material caused by the magnetic force generated at the end of the magnet part can be reduced, so the alignment of the carbon-based negative electrode active material contained in the negative electrode slurry can be reduced. There is an advantage in being able to manufacture a significantly higher cathode.

Figure 1 is a structural diagram schematically showing a conventional magnetic alignment device for a cathode.
Figure 2 is a structural diagram schematically showing a magnetic alignment device for a cathode according to the present invention.
Figure 3 is a cross-sectional view showing the structure of the magnet portion of the conventional magnetic alignment device and the magnetic alignment device of the present invention.

Since the present invention can be subject to various changes and can have various embodiments, specific embodiments will be described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

In the present invention, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Additionally, in the present invention, when a part of a layer, membrane, region, plate, etc. is described as being "on" another part, this includes not only being "directly on" the other part, but also cases where there is another part in between. . Conversely, when a part of a layer, membrane, region, plate, etc. is described as being “under” another part, this includes not only being “immediately below” the other part, but also cases where there is another part in between. Additionally, in this application, being placed “on” may include being placed not only at the top but also at the bottom.

In addition, in the present invention, "included as a main ingredient" means 50% by weight or more (or 50% by volume or more), 60% by weight or more (or 60% by volume or more) of the defined ingredient relative to the total weight (or total volume), Containing at least 70% by weight (or at least 70% by volume), at least 80% by weight (or at least 80% by volume), at least 90% by weight (or at least 90% by volume), or at least 95% by weight (or at least 95% by volume) It can mean. For example, "containing graphite as a main component as a negative electrode active material" means 50% by weight or more, 60% by weight, 70% by weight, 80% by weight, 90% by weight or more, or 95% by weight, based on the total weight of the negative electrode active material. This may mean containing more than % by weight, and in some cases, it may mean that the entire negative electrode active material is made of graphite and graphite contains 100% by weight.

In addition, in the present invention, “cross-sectional structure” refers to the structure of a surface cut perpendicularly based on the surface of the active layer.

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

Magnetic alignment device for cathode

In one embodiment, the present invention

A transfer unit that transfers the negative electrode current collector coated with the negative electrode slurry containing a carbon-based negative electrode active material in one direction; and

It includes a first magnet portion and a second magnet portion spaced apart from each other on the upper and lower portions of the conveyed negative electrode current collector,

The transfer unit transfers the negative electrode current collector so that it is adjacent to the second magnet unit based on the point where the separation distance between the first magnet unit and the second magnet unit is 1/2, and the transferred negative electrode current collector is relative to the second magnet unit. A magnetic alignment device for cathodes that are transferred to have a predetermined inclination is provided.

The magnetic alignment device for a negative electrode according to the present invention is a device applied when manufacturing a negative electrode used in a secondary battery, by applying a magnetic field to the surface of the negative electrode current collector on which the negative electrode slurry containing a carbon-based negative electrode active material is applied, that is, the surface of the negative electrode slurry. The carbon-based negative electrode active material contained in the negative electrode slurry can be aligned in a vertical direction with respect to the negative electrode current collector. Accordingly, the magnetic alignment device can implement uniform alignment of the carbon-based negative electrode active material contained in the negative electrode slurry, and the negative electrode manufactured in this way increases the mobility of lithium ions and reduces resistance during charging and discharging of the battery, thereby improving charging and discharging. This can result in improved performance.

Here, alignment in the direction perpendicular to the negative electrode current collector means that the crystal planes of the carbon-based negative electrode active material are aligned. Specifically, "the carbon-based negative electrode active material is vertically aligned with respect to the negative electrode current collector" refers to the crystal plane of the carbon-based negative electrode active material constituting spherical particles, specifically, the crystal plane that represents the planar direction of graphite with a two-dimensional structure among the crystal planes of graphite. This may mean that it is arranged vertically with respect to the surface of the negative electrode current collector. At this time, the plane direction of the graphite may have an average inclination of 60 to 120° with respect to the negative electrode current collector, and is preferably 70 to 110°; Alternatively, it may have an average tilt of 80 to 100°.

To this end, the magnetic alignment device 100 according to the present invention, as shown in FIG. 2, includes transfer units 1210 and 1220 that transfer a negative electrode current collector coated with a negative electrode slurry containing a carbon-based negative electrode active material in one direction; And it has a configuration including a first magnet portion and a second magnet portion (1110 and 1120) spaced apart from the upper and lower portions of the transported negative electrode current collector, respectively.

In the magnetic alignment device, the first magnet portion 1100a and the second magnet portion 1100b are disposed at the top and bottom of the running electrode sheet, respectively, and serve to apply a magnetic field to the surface of the cathode slurry (S). do.

The first magnet portion 1100a and the second magnet portion 1100b may each include a magnet to apply a magnetic field to the surface of the cathode slurry (S). Specifically, the first magnet unit (1100a) and the second magnet unit (1100b) include single magnets (1120a and 1120b) respectively disposed along the traveling direction of the cathode slurry (S); It may include support parts 1110a and 1110b to which the magnet is fixed.

At this time, the single magnets 1120a and 1120b may include electromagnets and/or permanent magnets. The electromagnet may include both a direct current electromagnet and an alternating current electromagnet. In addition, the permanent magnets include NdFeB-based magnets, SmCo-based magnets, Ferrite magnets, Alnico magnets, FeCrCo-based magnets, and Bond magnets (Nd-Fe-B-based, Sm-Fe-N-based, Sm-Co-based, Ferrite-based). It may include both magnets with ferromagnetic properties and magnets with soft magnetic properties, including the like.

In addition, the first magnet portion 1100a and the second magnet portion 1100b may be positioned along the traveling direction of the cathode slurry S to face each other and have opposite poles. For example, the N pole of the first magnet 1120a of the first magnet portion 1100a and the S pole of the second magnet 1120b of the second magnet portion 1100b are facing each other, or The S pole of the first magnet 1120a of 1100a may be arranged so that the N pole of the second magnet 1120b of the second magnet portion 1100b faces each other. In this way, when the electrode sheet passes between the space where the N pole and the S pole face each other, the carbon-based negative electrode active material is perpendicular to the negative electrode current collector (C) between the first magnet portion (1100a) and the second magnet portion (1100b). Sorting can be done more effectively.

In addition, the first magnet portion 1100a may be disposed on the upper part of the traveling electrode sheet and applied in a Halbach arrangement to apply a high magnetic field to the carbon-based negative electrode active material of the negative electrode slurry (S). Here, the Halbach array is a permanent magnet array, and can provide a magnet with a high magnetic field strength by gradually changing the magnetization direction of the magnet. When a magnet having a Halbach arrangement is used as the magnet 1120a of the first magnet portion 1100a, the negative electrode current collector C coated with the negative electrode slurry S is connected to the first magnet portion 1100a and the second magnet. Even if it is transported adjacent to the second magnet unit (1100b) based on the point (1/2D) where the separation distance (D) of the unit (1100b) is 1/2, the carbon is removed due to the high magnetic field of the first magnet unit (1100a). It is possible to achieve a high degree of alignment of the cathode active material.

In addition, the separation distance between the first magnet unit 1100a and the second magnet unit 1100b may be 10 mm to 50 mm, specifically 10 mm to 40 mm; 20 mm to 50 mm; Or it may be 15 mm to 45 mm. The present invention can more efficiently align the carbon-based negative electrode active material contained in the negative electrode slurry (S) by adjusting the separation distance between the first magnet portion (1100a) and the second magnet portion (1100b) within the above range.

Furthermore, in the magnetic alignment device 100, the transfer unit serves to transfer the negative electrode current collector on which the negative electrode slurry containing the carbon-based negative electrode active material is applied in one direction. To this end, the transfer unit can be applied without particular limitation as long as it is a method commonly used in the art to transfer electrode thin plates coated with electrode slurry during electrode manufacturing. For example, the transfer unit may use a roll-to-roll transfer method or a conveyor belt transfer method capable of applying a magnetic field.

In addition, the transfer unit may include means for controlling the position of the cathode slurry (S) passing between the first magnet unit (1100a) and the second magnet unit (1100b) to apply a magnetic field.

In a conventional lithium secondary battery using graphite, a technology has been proposed to orient the graphite contained in the negative electrode with a magnetic field in order to improve the electronic conductivity of the negative electrode by smoothly inserting and desorbing lithium ions and shortening the conduction path of electrons. there is. However, this technology applies a magnetic field by placing permanent magnets on the top and bottom of a thin metal plate coated with cathode slurry. Not only is it difficult to maintain a constant magnetic force, but the magnetic force is also generated at the end of the permanent magnet, that is, at the end of the magnetic field. A dragging phenomenon occurs and the graphite aligned perpendicularly to the thin metal plate collapses, so the graphite in the ultimately manufactured cathode active layer has a limit of low alignment.

However, in the present invention, when the negative electrode current collector (C) coated with the negative electrode slurry (S) passes through the space between the first magnet portion (1100a) and the second magnet portion (1100b) to apply a magnetic field, the separation distance between them By controlling, the strength of the magnetic field applied to the cathode slurry can be controlled to be strong at the entrance of the magnet unit and weakened as it is transferred to the outlet of the magnet unit. Through this, the present invention can suppress the occurrence of an attraction phenomenon caused by magnetic force at the end of the magnet part, that is, the end of the magnetic field, and the cathode manufactured accordingly can be implemented with a significantly high degree of alignment of the carbon-based anode active material.

Specifically, the transfer unit is connected to the second magnet unit (1100b) based on the point (1/2D) where the separation distance (D) between the first magnet unit (1100a) and the second magnet unit (1100b) is 1/2. The negative electrode current collectors (C) may be transferred so that they are adjacent to each other, but the transferred negative electrode current collectors (C) may be transferred so that the transferred negative electrode current collectors (C) have a predetermined inclination with respect to the second magnet portion (1100b). Here, “adjacent to the second magnet unit based on the point (1/2D) where the separation distance (D) between the first magnet unit (1100a) and the second magnet unit (1100b) is 1/2” means 1 This may mean that the separation distance between the negative electrode current collector (C) and the second magnet unit (1100b) is narrower than half the distance between the magnet unit (1100a) and the second magnet unit (1100b), which means that the negative electrode current collector (C) This may mean that the distance between the current collector C and the first magnet unit 1100a is greater than half the distance between the first magnet unit 1100a and the second magnet unit 1100b.

Additionally, the predetermined inclination of the negative electrode current collector (C) with respect to the second magnet portion (1100b) may be increased. That is, the negative electrode current collector (C) is discharged from the inlet (corresponding to point b in FIG. 3) introduced into the first magnet unit 1100a and the second magnet unit 1100b (corresponding to point d in FIG. 3). As it is transferred, the separation distance from the second magnet unit 1100b is transferred so that the inclination may increase. In this case, since the magnetic field at the entrance where the negative electrode current collector (C) is introduced into the first magnet unit (1100a) and the second magnet unit (1100b) is implemented to be stronger than the magnetic field at the outlet, the end of the magnet unit (i.e., the magnetic field As the magnetic field decreases toward the end, the interaction between the carbon-based anode active material and the magnet section can be minimized.

As an example, the separation distance between the negative electrode current collector (C) and the second magnet unit (1100b) is shorter than 1/2 of the separation distance between the first magnet unit (1100a) and the second magnet unit (1100b), and is expressed by the following equation 1 can be satisfied:

[Equation 1]

D _en ≤0.99D _ex

In equation 1,

D _en represents the separation distance between the negative electrode current collector and the second magnet portion at the inlet where the negative electrode current collector is introduced between the first magnet portion and the second magnet portion,

D _ex represents the separation distance between the negative electrode current collector and the second magnet portion at the outlet where the negative electrode current collector is discharged between the first magnet portion and the second magnet portion.

Equation 1 above shows the correlation between the separation distance between the negative electrode current collector (C) and the second magnet unit (1100b) at the inlet and outlet of the magnet unit, where the separation distance (D _en ) at the entrance of the magnet unit is the outlet of the magnet unit. This means that it is shorter than the separation distance (D _ex ) in .

Specifically, the separation distance (D _en ) at the entrance of the magnet unit may have a distance corresponding to 99% or less (D _en ≤0.99D _ex ) of the separation distance (D _ex ) at the exit of the magnet unit. is 95% or less (D _en ≤0.95D _ex ); 85% or less (D _en ≤0.85D _ex ); 75% or less (D _en ≤0.75D _ex ); 50% or less (D _en ≤0.50D _ex ); 1~40% (0.01D _ex ≤D _en ≤0.40D _ex ); 1~30% (0.01D _ex ≤D _en ≤0.30D _ex ); 1~20% (0.01D _ex ≤D _en ≤0.20D _ex ); 1~10% (0.01D _ex ≤D _en ≤0.10D _ex ); 5~30% (0.05D _ex ≤D _en ≤0.30D _ex ); 20~60% (0.20D _ex ≤D _en ≤0.60D _ex ); Alternatively, it may have a distance corresponding to 10 to 50% (0.10D _ex ≤D _en ≤0.50D _ex ). The present invention adjusts the ratio of the separation distance between the negative electrode current collector (C) and the second magnet unit (1100b) at the inlet and outlet of the magnet unit to the above range to prevent the generated at the end of the magnet unit due to a high ratio exceeding 99%. It is possible to prevent the drag phenomenon from being improved, and in some cases, it is possible to prevent the anode slurry from being pushed around due to a significantly low ratio of less than 1%.

In addition, the transfer unit may include means for adjusting the separation distance ratio (or deviation) between the negative electrode current collector (C) and the second magnet unit (1100b) at the inlet and outlet of the magnet unit.

Specifically, the transfer unit has a cathode electrode upstream of the inlet and downstream of the outlet of the magnet unit (more specifically, upstream of the inlet introduced between the first magnet unit 1100a and the second magnet unit 1100b and downstream of the outlet discharged). It may include a first transfer device 1210 and a second transfer device 1220 for transferring the current collector (C). In this case, the first transfer device 1210 is the negative electrode current collector (C) at the entrance of the magnet unit. ) and a tilt control device (not shown) for controlling the separation distance between the second magnet portion 1100b.

The tilt control device performs an upward and downward movement of the first transfer device in a direction perpendicular to the second magnet portion, that is, in a direction perpendicular to the surface on which the second magnet portion applies a magnetic field to the negative electrode slurry, so that the negative electrode current collector at the entrance of the magnet portion The separation distance between the and the second magnet part can be adjusted.

As an example, the transfer unit may include a first transfer roll 1210 and a second transfer roll 1220 upstream of the inlet and downstream of the magnet unit, respectively, and the first transfer roll 1210 may be connected to a second magnet. It may include a tilt control device (not shown) that induces an upward and downward movement of the first transfer roll 1210 in a direction perpendicular to the magnetic field application surface of the unit 1100b.

Meanwhile, the magnetic alignment device may further include a drying unit 1300 that dries the negative electrode slurry (S) in which the carbon-based negative electrode active material is aligned by the first magnet unit (1100a) and the second magnet unit (1100b). .

The drying unit 1300 includes a wall (not shown) that blocks the surrounding area except for the inlet and outlet through which the electrode sheet coated with the slurry (S) is introduced and discharged, and an electrode sheet on the wall on the side where the electrode sheet coated with the electrode slurry is pulled out. It is formed including a dryer (not shown) for drying.

When the electrode sheet (C) coated with the electrode slurry (S) enters through the inlet of the drying unit (1300), it receives energy such as light, wavelength, and heat supplied from the opposite wall. Therefore, it is preferable that the wall is made of an insulating material to prevent heat loss due to internal energy being transferred to the outside.

In addition, the dryer is not limited in its method, but may be configured to perform a two-stage drying process to maintain the alignment of the carbon-based negative electrode active material contained in the negative electrode active layer. Specifically, the dryer may include a first dryer that dries the cathode slurry using light and a second dryer that dries the cathode slurry using heat, and the first dryer and the second dryer operate continuously. The cathode slurry can be dried.

The first dryer is a device for temporarily drying the cathode slurry, and can irradiate light or wavelength to the surface of the cathode slurry as described above. Generally, drying a negative electrode slurry is performed by applying hot air at a high temperature. In this case, the drying time of the negative electrode slurry takes a long time, which may disrupt the alignment of the carbon-based negative electrode active material in the negative electrode slurry. In addition, when the temperature of the hot air is increased to solve this problem, the tendency of drying on the surface of the slurry increases, so a phenomenon in which high binders in the solvent are concentrated on the surface of the slurry according to the movement of the solvent (migration) occurs, causing the active material layer and the cathode to collect. There is a problem that the overall adhesion strength is low. The present invention can have a configuration in which the electrode slurry is temporarily dried by irradiating energy in the form of light or wavelength using a first dryer so that the negative electrode slurry can be dried while maintaining the high degree of alignment of the carbon-based negative electrode active material without such problems. there is. Such first dryers may include, for example, ultraviolet ray dryers, near-infrared rays dryers, far-infrared rays dryers, etc. Specifically, in order to realize a uniform drying speed of the electrode slurry, 1 ㎛ or more, more specifically 5 ㎛ or more, It may include a far-infrared dryer that emits energy with a wavelength of 10 ㎛ or more or 20 ㎛ or more. Unlike near-infrared ray dryers or infrared rays commonly used in the industry, the far-infrared dryer has good energy efficiency due to its long light or wavelength and can apply energy uniformly not only to the surface of the cathode slurry but also to the inside, so that the cathode slurry and the cathode current collector can be used in a short time. It has the advantage of increasing the adhesion between livers.

At this time, the first dryer may emit energy at a power density of 50 kW/m ² to 1,000 kW/m ² , specifically 50 kW/m ² to 500 kW/m ² ; of 50 kW/m ² to 250 kW/m ² ; Alternatively, energy can be released at power densities of 50 kW/m ² and 200 kW/m ² . The present invention can prevent uneven drying of the active material layer from being induced due to excessive power density by controlling the power density of the first dryer within the above range.

Additionally, the second dryer may apply heat to uniformly and completely dry the cathode slurry temporarily dried by light or wavelength. Such a second dryer may be included without particular limitation as long as it is commonly applied in the industry, but specifically may include a hot air dryer, a vacuum oven, etc., used alone or in combination.

By having the above-described configuration, the magnetic alignment device according to the present invention can reduce the attraction phenomenon of the carbon-based negative electrode active material due to the magnetic force generated at the end of the magnet portion, so the degree of alignment of the carbon-based negative electrode active material contained in the negative electrode slurry is significantly reduced. There is an advantage in being able to manufacture a high cathode.

Cathode manufacturing method

In addition, in one embodiment of the present invention,

Applying a negative electrode slurry containing a carbon-based negative electrode active material on the negative electrode current collector;

Aligning the carbon-based negative electrode active material contained in the negative electrode slurry using the magnetic alignment device according to the present invention described above; and

Provided is a method of manufacturing a negative electrode including the step of drying a negative electrode slurry in which carbon-based negative electrode active materials are aligned to form a negative electrode active layer.

The method for manufacturing a negative electrode according to the present invention is to apply a negative electrode slurry containing a carbon-based negative electrode active material on a negative electrode current collector and apply a magnetic field to the surface of the applied negative electrode slurry using the magnetic alignment device of the present invention described above to form a negative electrode. The carbon-based negative electrode active material in the slurry can be aligned perpendicular to the surface of the negative electrode current collector (or relative to the running direction of the electrode sheet), and then by continuously drying the negative electrode slurry, the carbon-based negative electrode active material can be vertically aligned. A maintained cathode active layer can be formed.

At this time, the method of manufacturing the negative electrode can achieve a significantly high degree of alignment of the carbon-based negative electrode active material with respect to the negative electrode current collector by using the magnetic alignment device described above, so the manufactured negative electrode has a mobility of lithium ions during charging and discharging of the battery. There is an advantage in that the charge and discharge performance is excellent as the resistance increases and the resistance decreases.

In the negative electrode manufacturing method, the steps of applying the negative electrode slurry to the negative electrode current collector and drying the negative electrode slurry may be performed in a manner commonly applied in the art.

In addition, in the step of aligning the carbon-based negative electrode active material contained in the negative electrode slurry using a magnetic alignment device, the application conditions of the magnetic field may be adjusted to increase the alignment efficiency of the carbon-based negative electrode active material. Specifically, the conditions for applying the magnetic field may be adjusted to increase the alignment efficiency of the carbon-based negative electrode active material. The degree of alignment can be adjusted by the strength of the magnetic field, application time, etc.

For example, the magnetic field may be applied at a magnetic field strength of 0.5 to 2.0T, more specifically 0.9 to 1.5T; 1.0~1.4T; 1.0~1.2T; 0.8~1.2%; Alternatively, a magnetic field strength of 0.5 to 1.2T may be applied.

Additionally, the magnetic field may be applied for a time of 0.1 to 20 seconds, more specifically 0.5 to 15 seconds; 0.5 to 12 seconds; 1 to 10 seconds; Alternatively, it may be applied for a time of 2 to 8 seconds. Meanwhile, the carbon-based negative electrode active material contained in the negative electrode slurry may include those commonly applied as carbon-based negative electrode active materials for lithium secondary batteries. Specifically, the carbon-based negative electrode active material refers to a material containing carbon atoms as a main component, and such carbon-based negative electrode active material may include graphite. The graphite may include one or more of natural graphite and artificial graphite, but preferably includes natural graphite or a mixture of natural graphite and artificial graphite.

Anode for lithium secondary battery

Furthermore, in one embodiment of the present invention,

Provided is a negative electrode for a lithium secondary battery manufactured using the magnetic alignment device according to the present invention described above.

The negative electrode for a lithium secondary battery according to the present invention includes a negative electrode active layer containing a carbon-based negative electrode active material on at least one surface of the negative electrode current collector. The negative electrode active layer is a layer that realizes the electrical activity of the negative electrode, and is manufactured by applying an electrode slurry containing a negative electrode active material that implements an electrochemical redox reaction during charging and discharging of the battery to both sides of the electrode current collector, then drying and rolling it. do. The negative electrode active layer includes a carbon-based negative electrode active material to realize electrical activity through a reversible redox reaction when charging and discharging the battery. Specifically, the carbon-based negative electrode active material refers to a material containing carbon atoms as a main component, and such carbon-based negative electrode active material may include graphite. The graphite may include one or more of natural graphite and artificial graphite, but preferably includes natural graphite or a mixture of natural graphite and artificial graphite.

The carbon-based negative electrode active material is preferably a spherical graphite granule formed by gathering a plurality of flake-shaped graphite. As flaky graphite, in addition to natural graphite and artificial graphite, mesophase calcined carbon (bulk mesophase) made from tar and pitch, cokes (raw coke, green coke, pitch coke, needle coke, petroleum coke, etc.) are used as graphite. and those granulated using a plurality of natural graphites with high crystallinity are particularly preferable. Additionally, one graphite granulated product may be formed by gathering 2 to 100 pieces of scale-shaped graphite, preferably 3 to 20 pieces.

This carbon-based negative electrode active material, specifically graphite, may have a spherical particle shape. In this case, the sphericity of the graphite particles may be 0.75 or more, for example, 0.75 to 1.0; 0.75 to 0.95; 0.8 to 0.95; Or it may be 0.90 to 0.99. Here, “degree of sphericity” may mean the ratio of the shortest diameter (minor diameter) and the longest diameter (major axis) among any diameters passing through the center of the particle. If the degree of sphericity is 1, the shape of the particle means that it is spherical. The degree of sphericity can be measured using a particle shape analyzer. The present invention can improve the capacity of the battery by realizing a high electrical conductivity of the negative electrode active layer by implementing the shape of the carbon-based negative electrode active material close to a spherical shape, and can increase the specific surface area of the negative electrode active material, thereby improving the gap between the negative electrode active layer and the current collector. It has the advantage of improving adhesion.

In addition, the carbon-based negative active material may have an average particle diameter (D ₅₀ ) of 0.5 ㎛ to 10 ㎛, specifically 2 ㎛ to 7 ㎛; 0.5㎛ to 5㎛; Alternatively, it may have an average particle diameter (D ₅₀ ) of 1㎛ to 3㎛.

It may be advantageous to make the average particle size of spherical natural graphite smaller in order to maximize the degree of disorder in the direction of expansion for each particle to prevent expansion of the particles due to charging of lithium ions. However, when the particle size of natural graphite is less than 0.5 ㎛, a large amount of binder is required due to an increase in the number of particles per unit volume, and the degree of sphericity and spheronization yield may be low. On the other hand, if the maximum particle diameter exceeds 10 ㎛, expansion becomes severe and as charging and discharging are repeated, the bonding between particles and the bonding between particles and the current collector deteriorates, which can greatly reduce cycle characteristics.

In the negative electrode active layer containing such a carbon-based negative electrode active material, alignment of the carbon-based negative electrode active material can be achieved in a direction perpendicular to the negative electrode current collector by the magnetic alignment device according to the present invention described above. The present invention can lower the electrode resistance by aligning the crystal planes of the carbon-based negative electrode active material contained in the negative electrode active layer in a certain direction, and through this, the charging performance of the negative electrode active layer can be further improved.

Here, the degree of alignment (i.e., degree of orientation) of the carbon-based negative active material (eg, graphite) can be determined through crystal plane analysis of the graphite.

As an example, in the negative electrode active layer, the carbon-based negative electrode active material is vertically aligned with respect to the negative electrode current collector, and when measuring to 0.6 can be satisfied:

[Equation 2]

OI = I ₀₀₄ /I ₁₁₀

In equation 2,

I ₀₀₄ represents the area of the peak representing the [0,0,4] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer,

I ₁₁₀ represents the area of the peak representing the [1,1,0] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer.

Equation 2 above can be an indicator of the degree to which the crystal structure of the spherical carbon-based negative electrode active material is aligned in a certain direction, specifically in a direction perpendicular to the surface of the negative electrode current collector, when measured by X-ray diffraction. Specifically, during 0.2°, and the peaks represent 2θ=26.5±0.2°, 42.4±0.2°, 43.4±0.2°, 44.6±0.2°, 54.7±0.2°, 77.5±0.2°, that is, [0,0,2 ] surface, [1,0,0] surface, [1,0,1]R surface, [1,0,1]H surface, [0,0,4] surface, [1,1,0] surface. It represents. The peak that appears at 2θ=43.4±0.2° overlaps the peak corresponding to the [1,0,1]R plane of the carbon-based material and the [1,1,1] plane of the current collector, for example, Cu. It can be seen as having appeared.

Among these, the area ratio of the peak at 2θ = 77.5 ± 0.2° representing the [1,1,0] plane and the peak at 2θ = 54.7 ± 0.2° representing the [0,0,4] plane, specifically, the peak The degree of alignment (O.I) of graphite can be measured through the area ratio obtained by integrating the intensity of . Here, the peak at 2θ = 54.7 ± 0.2° is a peak representing the [0,0,4] plane with an inclination to the negative electrode current collector among the crystal planes of graphite, so the degree of alignment (O.I) has a value close to 0. As the value increases, the inclination to the negative electrode current collector surface is closer to 90°, and as the value increases, it may mean that the inclination to the negative electrode current collector surface is closer to 0° or 180°. In this respect, in the negative electrode active layer according to the present invention, the carbon-based negative electrode active material is vertically aligned with respect to the negative electrode current collector, so the degree of alignment (O.I.) of the graphite may be low compared to the case where the carbon-based negative electrode active material is not vertically aligned. Specifically, the degree of alignment of the carbon-based negative electrode active material contained in the negative electrode active layer may be 0.1 to 0.6, and more specifically, 0.15 to 0.6; 0.15 to 0.5; 0.2 to 0.5; 0.2 to 0.4; 0.25 to 0.45; Or it may be 0.3 to 0.5. As another example, the cathode active layer may have an alignment degree of 1.0 or less according to Equation 3 below when measured by a near-end X-ray fluorescence spectrometer (NEXAFS):

[Equation 3]

(In Equation 3 above, S _60/0 is the peak intensity ratio (I0 _{B / A} ) indicates the value of ).

The near edge X-ray absorption spectrum is also called the Near Edge X-ray Absorbance Fine Structure (NEXAFS) spectrum. The near edge This is an absorption spectrum observed as each inner shell electron) absorbs the energy of irradiated X-rays and is excited to various unoccupied colevels.

Here, the co-level where electrons in the inner angle level are excited is the π* level that is attributed to the antibonding orbital of the sp2 bond, which reflects the crystallinity (base plane, orientation, etc.) in natural graphite, and the disordered crystallinity (edge plane, non-orientation, etc.) There is a σ* level that is attributed to the antibonding orbital of an sp3 bond, or a colevel that is attributed to an antibonding orbital of a C-H bond or C-O bond. In graphite, which has a crystal structure in which a hexagonal network structure is stacked by sp2 bonds, the plane of the hexagonal network plane (AB plane, described later) is the base plane, and the plane where the ends of the hexagonal network appear is the edge plane. On the edge surface, the carbon may have -C=O, etc. at the terminal, so the sp3 bond ratio may be high.

In addition, unlike X-ray photoelectron spectroscopy (XPS), which measures the bond energy between atoms constituting a compound, the near-end NEXAFS spectrum reflects the local structure around the carbon atoms, including excited inner shell electrons, as well as the measured graphite particles. Only the surface structure of can be reflected. Therefore, the present invention can measure the crystal state (orientation) of graphite, a carbon-based negative electrode active material forming spherical particles, by using the near-end NEXAFS spectrum.

Meanwhile, in the measurement of the near-end NEXAFS spectrum, synchronized light with a fixed incident angle can be irradiated to the sample. The energy of the irradiated synchronized light is scanned from 280 eV to 320 eV, and the energy flowing into the sample is used to compensate for the photoelectrons emitted from the sample. This can be performed by total electron quantification, which measures the sample current. Specifically, in order to more quantitatively measure the degree of alignment of the carbon-based negative electrode active material contained in the negative electrode active layer, the present invention can measure the degree of alignment (S _60/0 ) shown in Equation 3.

In general, synchronized light has high linear polarization, so when the incident direction of synchronized light is parallel to the bond axis direction of the sp2 bond (-C=C-) of the surface graphite crystal, absorption is attributed to the transition from the C1s level to the π* level. The peak intensity increases, and conversely, when the peaks are perpendicular to each other, the absorption peak intensity decreases. Therefore, in highly oriented graphite (e.g., HOPG, single-crystal graphite), the graphite crystals that form sp2 bonds near the surface are highly aligned, so the spectral shape changes significantly when the incident angle of synchronized light to the sample is changed. On the other hand, low-orientation side edges (e.g., non-graphitic carbon deposited films) have low orientation of the carbon material that forms sp2 bonds near the surface, so the spectral shape hardly changes even if the angle of incidence of synchronized light to the sample is changed. .

In addition, the cathode active layer may absorb any second absorption peak for any first absorption peak intensity (I _A ) when measuring the near-end NEXAFS spectrum (i.e., near-end X-ray fluorescence spectrometry (NEXAFS)) at different angles of incidence with respect to the cathode active layer surface. The ratio (I _B/A ) of the peak intensity ( _IB ) may change depending on the angle of incidence, which may mean that the carbon-based anode active material contained in the measured anode active layer is arranged in a regular manner (i.e., highly oriented). there is. On the other hand, if the ratio I does not change depending on the angle of incidence, it may mean that the carbon-based negative electrode active material contained in the measured negative electrode active layer is arranged irregularly (i.e., has low orientation).

Accordingly, the present invention measures the near-end NEXAFS spectrum (i.e., near-end 60°), and the absorption peak attributed to the transition from C1s level to π* level for each incident angle (peak A=287±0.2eV). The absorption attributed to transition from C1s level to σ* level for intensity. After obtaining the ratio (I _B/A ) of the intensity of the peak (peak B = 293 ± 0.2 eV), the ratio of the intensity ratio between the angles of incidence (60° and 0°) (S _60/0 = I60 _B/A /I0 _B/ By calculating _A ), the degree of alignment of the carbon-based negative active material can be quantitatively measured.

In other words, the degree of alignment of the carbon-based anode active material contained in the anode active layer is i) as shown in Equation 4, the absorption peak attributed to the transition from the C1s level to the π* level measured at an incident angle of 60° (peak A = 287 ±0.2 eV) Calculate the ratio (I60 _B /A) of the intensity (I60 _B ) of the absorption peak (peak B=293±0.2 eV) attributed to the transition from the C1s level to the σ* level for the intensity (I60 _A ); ii) σ* from the C1s level for the intensity (I0 _A ) of the absorption peak (peak A=287±0.2eV) attributed to the transition from the C1s level to the π* level measured at an angle of incidence of 0°, as shown in equation 5. After calculating the ratio (I0 _B/A ) of the intensity (I0 _B ) of the absorption peak (peak B=293±0.2 eV) attributed to the transition to the level; iii) can be evaluated by finding their ratio (S _60/0 = I60 _B/A /I0 _B/A ) as shown in equation 3:

[Equation 4]

[Equation 5]

In Equation 4 and Equation 5,

I60 _A represents the intensity of the peak with the highest intensity among the peaks present at 286 ± 1.0 eV when the angle of incidence is 60°.

I60 _B represents the intensity of the peak with the highest intensity among the peaks present at 292.5 ± 1.0 eV when the angle of incidence is 60°,

I0 _A represents the intensity of the peak with the highest intensity among the peaks present at 286 ± 1.0 eV when the angle of incidence is 0°.

I0 _B represents the intensity of the peak with the highest intensity among the peaks present at 292.5 ± 1.0 eV when the angle of incidence is 0°.

Here, the closer S _60/0 is to 1, the lower the alignment of the graphite crystals is, and the closer it is to 0, the higher the alignment of the graphite crystals is. The anode active layer according to the present invention can satisfy the value (S _60/0 ) according to Equation 3 as 1.0 or less, and more specifically, 0.9 or less; 0.8 or less; 0.7 or less; 0.1 to 0.7; Alternatively, 0.3 to 0.7 may be satisfied.

Furthermore, the negative electrode active layer induces uniform vertical alignment of the carbon-based negative electrode active material with respect to the negative electrode current collector, so that the alignment deviation of the carbon-based negative electrode active material arbitrarily measured in a unit area can be low.

As an example, the negative electrode active layer has an alignment deviation of the carbon-based negative active material expressed by Equation 2 when measuring X-ray diffraction spectroscopy (XRD) at any three points present in a unit area (10 cm may be less than 5% based on the average value, and may specifically be less than 4%, less than 3%, less than 2%, or less than 1%.

As another example, the negative electrode active layer is aligned with the carbon-based negative electrode active material expressed by Equation 3 when measured by a near-end The degree deviation may be less than 5% of the average value, and specifically may be less than 4%, less than 3%, less than 2%, or less than 1%.

Meanwhile, the negative electrode active layer according to the present invention may optionally further include a conductive material, binder, and other additives, if necessary, along with the negative electrode active material.

The conductive material may include one or more types of carbon black, acetylene black, Ketjen black, carbon nanotubes, carbon fiber, etc., but is not limited thereto.

As an example, the anode active layer may contain carbon black, carbon nanotubes, carbon fiber, etc. as a conductive material alone or in combination.

At this time, the content of the conductive material may be 0.1 to 10 parts by weight based on 100 parts by weight of the total negative electrode active layer, and 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 It may be 0.5 to 2 parts by weight. By controlling the content of the conductive material within the above range, the present invention can prevent the charge capacity from decreasing due to an increase in the resistance of the negative electrode due to a low content of the conductive material, and the content of the negative electrode active material decreases due to an excessive amount of the conductive material. This can prevent problems such as a decrease in charging capacity or rapid charging characteristics due to an increase in the loading of the cathode active layer.

In addition, the binder is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector, and can be appropriately applied as long as it does not deteriorate the electrical properties of the electrode. Specifically, the binder is vinylidene fluoride-hexafluoropropylene. Copolymer (PVDF-co-HFP), polyvinylidenefluoride (PVdF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch , hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene butadiene rubber and fluorine. It may include any one or more selected from the group consisting of rubber.

The content of the binder may be 0.1 to 10 parts by weight, 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, based on 100 parts by weight of the total negative electrode active layer. The present invention can prevent the adhesion of the active layer from being reduced due to a low content of the binder or the electrical properties of the electrode from being reduced due to an excessive amount of binder by controlling the content of the binder contained in the negative electrode active layer within the above range.

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, copper In the case of stainless steel, surface treatment with carbon, nickel, titanium, silver, etc. may be used. In addition, the average thickness of the negative electrode current collector may be appropriately applied in the range of 1 to 500 ㎛ considering the conductivity and total thickness of the negative electrode being manufactured.

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

However, the following examples and experimental examples only illustrate the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

Examples and comparative examples. Manufacturing of negative electrode for lithium secondary battery

A negative electrode is manufactured using the magnetic alignment device of the present invention having a structure as shown in Figure 1 or Figure 2, but the tilt of the negative electrode current collector with respect to the surface of the second magnet unit is manufactured using a tilt control device introduced in the first transfer unit. was adjusted as shown in Table 1 below to prepare a negative electrode for a lithium secondary battery.

Specifically, first, natural graphite was prepared as a negative electrode active material, and 97 parts by weight of the negative electrode active material and 3 parts by weight of styrene-butadiene rubber (SBR) were mixed with water to form a negative electrode slurry, and then roll-to-roll transfer (transfer speed: 5 m/min) ) The cathode slurry was cast using a die coater on the copper thin plate being formed. At this time, the cathode slurry was cast to have an average thickness of 330 ㎛ along the traveling direction of the copper thin plate.

Then, a magnetic field was applied to the cathode slurry by moving the thin copper plate so that the applied cathode slurry passed between the first magnet portion and the second magnet portion. Here, the separation distance between the first magnet unit and the second magnet unit was adjusted to be 20 mm (half of the separation distance: 10 mm), and the applied magnetic field strength was 1.0 T. In addition, the copper thin plate introduced between the first magnet unit and the second magnet unit uses the tilt control device introduced in the first transfer unit, as shown in Table 1 below, i) the average separation distance from the second magnet unit ( Specifically, (maximum separation distance between the thin copper plate and the second magnet section within the magnet section) + (half the value of (minimum separation distance between the thin copper plate and the second magnet section)), ii) the separation distance at the outlet of the second magnet section (D _ex ), and iii) the separation distance (D _en ) at the entrance of the second magnet unit was adjusted.

Additionally, in order to dry the negative electrode slurry to which a magnetic field was applied, a thin copper plate to which a magnetic field was applied to the negative electrode slurry was moved to the drying section and the negative electrode slurry was dried to produce a negative electrode for a lithium secondary battery.

Magnetic alignment device structure Average separation distance between the negative electrode current collector and the second magnet section D _ex D _en Comparative Example 1 Figure 1 10 mm 10 mm _1.0Dex Example 1 Figure 2 4.73 mm 9 mm _0.05Dex Example 2 Figure 2 6.75 mm 9 mm _0.50Dex Example 3 Figure 2 8.55 mm 9 mm _0.90Dex

Experiment example. Evaluation of alignment uniformity of carbon-based negative electrode active material

As for the performance of the magnetic alignment device according to the present invention, the following experiment was performed to evaluate the alignment uniformity of the carbon-based negative electrode active material.

Specifically, the cathode slurry was casted on a thin copper plate in the same manner as in Example 1, and the casted copper plate was placed in the first magnet portion and the second magnet portion of each magnetic alignment device used in Examples 1 to 3 and Comparative Example 1. passed between them. Then, before the copper thin plate completely passed between the first magnet portion and the second magnet portion, the applied magnetic field was removed, and the cathode slurry was dried. Then, the dried cathode slurry, that is, the cathode active layer, is measured by performing From the measured results, the degree of alignment of graphite obtained from Equation 2 was calculated.

Separately, negative electrodes were manufactured by carrying out the same method as Examples 1 to 3 and Comparative Example 1, and the average of the first unit area (5 cm × 5 cm) and the negative electrode slurry present on the surface of the negative electrode active layer of the manufactured negative electrode was obtained. The second unit area (5 cm × 5 cm) existing within the casting area was arbitrarily set to a thickness of 100 μm. Then, the spectra were measured by performing X-ray diffraction spectroscopy (XRD) and near-end

At this time, the measurement conditions of the near-end X-ray fluorescence spectrometer (NEXAFS) and X-ray diffraction (XRD) are as follows:

① Near-edge X-ray fluorescence spectrometer (NEXAFS)

- Acceleration voltage: 1.0GeV~1.5GeV

- Accumulated current: 80~350mA

- Angle of incidence: 60° or 0°

② X-ray diffraction (XRD)

- Target: Cu (Kα-ray) graphite monochromator

- Slit: Divergent slit = 1 degree, Receiving slit = 0.1 mm, Scattering slit = 1 degree

From the spectrum measured under the above conditions, the average degree of alignment (i.e., the average value of the degree of alignment at each point) of each carbon-based negative electrode active material according to Equation 2 and Equation 3 was calculated, respectively. The results are shown in Table 2.

[Equation 2]

OI = I ₀₀₄ /I ₁₁₀

In equation 2,

I ₀₀₄ represents the area of the peak representing the [0,0,4] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer,

I ₁₁₀ represents the area of the peak representing the [1,1,0] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer.

[Equation 3]

In equation 3,

S _60/0 represents the value of the peak intensity ratio (I0 B/A) at an incident angle of 60° to the peak intensity ratio (I60 _B/A ) at an incident angle of 0° when measured by a near-end X-ray fluorescence spectrometer _(NEXAFS ). .

Comparative Example 1 Example 1 Example 2 Example 3 In the magnet section
By location
alignment chart
(I ₀₀₄ /I ₁₁₀ ) a 7.51 7.47 7.53 7.48 b 4.98 4.34 4.48 4.65 c 2.21 1.97 2.02 2.09 d 0.23 0.24 0.24 0.23 e 0.46 0.28 0.34 0.39 I ₀₀₄ /I ₁₁₀ 0.46 0.28 0.34 0.39 S _60/0 1.05 0.69 0.68 0.71

As shown in Table 2, the negative electrode manufactured using the magnetic alignment device according to the present invention was confirmed to have a significantly high degree of alignment of the carbon-based negative electrode active material contained in the negative electrode active layer. This means that the magnetic alignment device according to the present invention applies a magnetic field by introducing a magnet portion to the upper and lower portions of the negative electrode current collector to which the negative electrode slurry is applied, but while the negative electrode current collector passes through the magnet portion, the magnet portion introduced to the lower portion and the negative electrode collector This means that the attraction phenomenon of the carbon-based negative electrode active material due to the magnetic force generated at the end of the magnet unit can be reduced by transferring the negative electrode current collector so that the overall separation distance has a predetermined slope.

From these results, it can be seen that the magnetic purifying device according to the present invention can produce a negative electrode with a significantly high degree of alignment of the carbon-based negative electrode active material contained in the negative electrode slurry.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art or have ordinary knowledge in the relevant technical field will understand that it does not deviate from the spirit and technical scope of the present invention as set forth in the claims to be described later. It will be understood that various modifications and changes can be made to the present invention within the scope.

Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be determined by the scope of the patent claims.

1: Conventional magnetic alignment device 2 and 200: Coating portion
3 and 300: wound negative electrode current collector
10a and 10b: first magnet portion and second magnet portion
11a and 11b: first support and second support
12a and 12b: first single magnet and second single magnet
20: drying section
100: Magnetic alignment device of the present invention
1100a and 1100b: first magnet portion and second magnet portion
1110a and 1110b: first support and second support
1120a and 1120b: first single magnet and second single magnet
1210 and 1220: first transfer roller and second transfer roller
1300: Drying unit
C: Cathode current collector S: Cathode slurry
D: Separation distance between the first magnet section and the second magnet section

Claims (10)

A transfer unit that transfers the negative electrode current collector coated with the negative electrode slurry containing a carbon-based negative electrode active material in one direction; and
It includes a first magnet portion and a second magnet portion spaced apart from each other on the upper and lower portions of the conveyed negative electrode current collector,
The transfer unit transfers the negative electrode current collector so that it is adjacent to the second magnet unit based on the point where the separation distance between the first magnet unit and the second magnet unit is 1/2, and the transferred negative electrode current collector is relative to the second magnet unit. A magnetic alignment device for the cathode that is transported to have a predetermined inclination.
According to paragraph 1,
A magnetic alignment device for the negative electrode in which the negative electrode current collector is transferred from the inlet where the first and second magnet parts are introduced to the outlet where it is discharged, so that the separation distance from the second magnet part increases.
According to paragraph 1,
The separation distance between the negative electrode current collector and the second magnet portion is,
Shorter than 1/2 of the separation distance between the first magnet portion and the second magnet portion,
A magnetic alignment device for the cathode that satisfies Equation 1 below:
[Equation 1]
D _en ≤0.99D _ex
In equation 1,
D _en represents the separation distance between the negative electrode current collector and the second magnet portion at the inlet where the negative electrode current collector is introduced into the first magnet portion and the second magnet portion,
D _ex represents the separation distance between the negative electrode current collector and the second magnet portion at the outlet where the negative electrode current collector is discharged from the first magnet portion and the second magnet portion.
According to paragraph 1,
The transfer department,
The negative electrode current collector includes a first transfer device and a second transfer device at the inlet through which the first magnet portion and the second magnet portion are introduced and the outlet through which the negative electrode current collector is discharged, respectively;
The first transfer device is a magnetic alignment device for the cathode including a tilt control device that controls the separation distance between the negative electrode current collector and the second magnet portion to be transported by performing an upward and downward movement in the vertical direction with respect to the second magnet portion.
According to paragraph 1,
A magnetic alignment device for a cathode wherein the separation distance between the first magnet portion and the second magnet portion is 10 mm to 50 mm.
According to paragraph 1,
A magnetic alignment device of a cathode including magnets having opposite poles to the first magnet portion and the second magnet portion.
According to paragraph 1,
The magnetic alignment device is a magnetic alignment device for a negative electrode, further comprising a drying section for drying the negative electrode slurry in which the carbon-based negative electrode active material is aligned by the first magnet section and the second magnet section.
Applying a negative electrode slurry containing a carbon-based negative electrode active material on the negative electrode current collector;
Aligning the carbon-based negative electrode active material contained in the negative electrode slurry using the magnetic alignment device according to claim 1; and
A method of manufacturing a negative electrode comprising the step of drying a negative electrode slurry in which carbon-based negative electrode active materials are aligned to form a negative electrode active layer.
According to clause 8,
A method of manufacturing a negative electrode in which the carbon-based negative electrode active material includes at least one of natural graphite and artificial graphite.
According to clause 8,
The negative electrode active layer is a method of manufacturing a negative electrode having an alignment degree of 0.1 to 0.6 of the carbon-based negative electrode active material represented by the following formula 2:
[Equation 2]
OI = I ₀₀₄ /I ₁₁₀
In equation 2,
I ₀₀₄ represents the area of the peak representing the [0,0,4] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer,
I ₁₁₀ represents the area of the peak representing the [1,1,0] crystal plane when measuring X-ray diffraction spectroscopy (XRD) for the cathode active layer.

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