KR20210158589A - Electrode slurry coating system and coating method using the same - Google Patents

Abstract

The present invention relates to an electrode slurry system including a coating roll having a predetermined region formed in a double structure, and a method thereof, wherein in spite of a temperature change of electrode slurry, the electrode slurry can be uniformly coated by constantly controlling a gap between a discharge hole of an electrode slurry slot die and a current collector layer.

Description

Electrode slurry coating system and coating method using the same

The present invention relates to an electrode slurry coating system and a coating method using the same, and to an electrode slurry coating system having excellent coating uniformity and a coating method using the same.

With the increase in technology development and demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among them, a lithium secondary battery is widely used as an energy source for various electronic products as well as various mobile devices in that it has high energy density and operating voltage and excellent preservation and lifespan characteristics.

As the field of application for secondary batteries is widened, the demand for higher-capacity secondary batteries is rapidly increasing. As a method of increasing the capacity of a secondary battery, research is being conducted on a technique for increasing the loading amount of the electrode mixture layer. Electrodes for secondary batteries are manufactured through drying and rolling processes after coating the electrode slurry on a current collector. However, in order to increase the loading of the electrode mixture layer, it is necessary to coat a large amount of electrode slurry on the current collector. In order to increase the coating amount of the electrode slurry, a higher level of coating uniformity is required.

1 is a perspective view showing a conventional electrode slurry coating system. Referring to FIG. 1 , the electrode slurry slot die 20 discharges the electrode slurry on the current collector layer 30 passing over the coating roll 10 rotating in one direction (R). Specifically, the current collector layer 30 is transferred in the MD direction (Mechanical Direction, F) while passing on the coating roll 10 rotating in one direction (R). The electrode slurry slot die 20 discharges the electrode slurry on the current collector layer 30 through the electrode slurry discharge unit 21 , and through this, the electrode slurry of a specific width D is coated on the current collector layer 30 . A portion 31 is formed.

In order to keep the thickness of the electrode slurry coating part 31 constant, the distance between the electrode slurry discharge part 21 and the coating roll 10 should be controlled uniformly. Conventionally, there has been an attempt to change the position or outer diameter of the coating roll 10 in consideration of the external temperature of the electrode slurry coating system.

However, this attempt does not take into account the temperature of the discharged electrode slurry. The outside temperature of the electrode slurry coating system can be controlled through an air conditioning system in the facility. However, the temperature change of the electrode slurry discharged from the electrode slurry slot die 20 is induced within a certain range due to a variable such as a process step or a heating time. Typically, the electrode slurry slot die 20 is designed and manufactured with the intention of discharging electrode slurry of a specific temperature. The temperature change of the electrode slurry induces a minute displacement or deformation of the electrode slurry discharge part 21 , which causes the thickness of the electrode slurry coating part 31 to be non-uniform.

Therefore, there is a need for a technique capable of implementing coating uniformity in response to the temperature of the electrode slurry discharged from the slot die when coating the electrode slurry.

Japanese Laid-Open Patent Publication No. 2018-158278

An object of the present invention is to provide an electrode slurry coating system capable of implementing coating uniformity in response to the temperature of the electrode slurry discharged from a slot die, and a coating method using the same.

The present invention provides an electrode slurry coating system. In one example, the electrode slurry slot die for discharging the electrode slurry; a coating roll for supporting and transferring the current collector layer; a current collector layer on which the electrode slurry discharged from the electrode slurry slot die is coated on one side or both sides but transferred along the coating roll; and a temperature sensor for measuring the temperature of the electrode slurry discharged from the electrode slurry slot die.

At this time, the coating roll may include a cylindrical roller body having a hollow formed therein; a rotating shaft fastened to both side ends of the roller body to support the roller body and to apply a rotational force to the roller body; and a temperature control member positioned inside the roller body to heat or cool the roller body, wherein the roller body is divided into a central part and a peripheral part on both sides of the central part based on the width direction (W), the outer diameter of the central part (C _out ) and the difference between the inner diameter (C _{in ) (C out} - C _in ) and the outer diameter (S _out ) and the inner diameter (S _in ) of the _{periphery (S out} - S _in ) have different structures.

In one example, the roller body has a structure satisfying Equation 1 below:

[Equation 1]

C _out - C _in > S _out - S _in

In Equation 1, C _out and C _in represent the outer diameter and inner diameter of the center in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral part in the hollow structure, respectively. In a specific example, the roller body has a structure _in which the difference between _{the outer diameter (C out} ) and the inner diameter (C _{in ) of the hollow structure from the center to the periphery (C out} - C _in ) sequentially or continuously decreases.

In another example, the roller body has a structure that satisfies the following Equation 2:

[Equation 2]

C _out - C _in < S _out - S _in

In Equation 2, C _out and C _in represent the outer diameter and inner diameter of the central portion in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral portion in the hollow structure, respectively. In a specific example, the roller body, the difference between the outer diameter (C _out) to the inner diameter (C _in) toward the periphery of the hollow in the center - a (C _{out in} C) is a structure for sequentially or continuously increased.

In one example, when the coating roll is heated by the temperature control member, the coating roll forms a crown structure, and when the coating roll is cooled by the temperature control member, the coating roll forms an inverted crown structure.

Furthermore, in the electrode slurry coating system, when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the temperature control member heats the coating roll, and the temperature of the electrode slurry measured by the temperature sensor is preset When the temperature is less than the reference temperature, the temperature control member may further include a control unit for controlling to cool the coating roll.

In one example, the temperature control member is a heat medium flow path formed in the width direction of the roller body. In a specific example, the temperature control member includes a heating coil and a cooling passage.

In addition, the present invention provides an electrode slurry coating method using the electrode slurry coating system described above. In one example, when the temperature of the electrode slurry measured by the temperature sensor is greater than the preset reference temperature, the temperature control member heats the coating roll, and the temperature of the electrode slurry measured by the temperature sensor is less than the preset reference temperature. In this case, the temperature control member controls to cool the coating roll.

In a specific example, the preset reference temperature is characterized in that it is set within the range of 22 to 24 ℃.

In one example, when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the coating roll is heated in a range of 25 to 50°C.

In another example, when the temperature of the electrode slurry measured by the temperature sensor is less than a preset reference temperature, the coating roll is cooled in a range of 5 to 20°C.

The electrode slurry system and method according to the present invention enables uniform electrode slurry coating by constantly controlling the gap between the discharge port of the electrode slurry slot die and the current collector layer despite the temperature change of the electrode slurry.

1 is a perspective view of a conventional electrode slurry coating system.
2 is a cross-sectional view of a coating roll applied to an electrode slurry coating system according to an embodiment of the present invention.
3 is a right cross-sectional view of a coating roll applied to an electrode slurry coating system according to an embodiment of the present invention.
4 is a front view of an electrode slurry coating system according to an embodiment of the present invention.
5 is a result of measuring the temperature distribution and displacement according to the heating of the coating roll.
6 is a front view of an electrode slurry coating system according to another embodiment of the present invention.
7 is a result of measuring the temperature distribution and displacement according to the cooling of the coating roll.
8 is a cross-sectional view of a coating roll applied to an electrode slurry coating system according to another embodiment of the present invention.
9 is a right cross-sectional view of a coating roll applied to an electrode slurry coating system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined in

The present invention provides an electrode slurry coating system. In one embodiment, the electrode slurry slot die for discharging the electrode slurry; a coating roll for supporting and transferring the current collector layer; a current collector layer on which the electrode slurry discharged from the electrode slurry slot die is coated on one side or both sides but transferred along the coating roll; and a temperature sensor for measuring the temperature of the electrode slurry discharged from the electrode slurry slot die.

In particular, the coating roll may include a cylindrical roller body having a hollow formed therein; a rotating shaft fastened to both side ends of the roller body to support the roller body and to apply a rotational force to the roller body; and a temperature control member positioned inside the roller body to heat or cool the roller body, wherein the roller body is divided into a central part and a peripheral part on both sides of the central part in the width direction, the outer diameter of the central part (C _out) ) and the difference between the inner diameter (C _{in ) (C out} - C _in ) and the outer diameter (S _out ) and the inner diameter (S _in ) of the _{periphery (S out} - S _in ) have different structures.

In the present invention, it was confirmed that the discharging portion of the slurry slot die was displaced or deformed according to the temperature of the electrode slurry discharged from the electrode slurry slot die. The shape of the coating roll is changed to correspond to the displacement or deformation of the discharging part of the slow die to achieve uniform discharging. Specifically, the electrode slurry slot die is designed based on a case where the temperature of the electrode slurry is a specific temperature, for example, 23°C. However, in the actual process, the discharge temperature of the electrode slurry varies in the range of, for example, 20 to 26°C. This change in the discharge temperature of the electrode slurry causes a slight deformation or displacement of the discharge portion of the electrode slurry slot die. Specifically, in the discharge portion of the electrode slurry slot die, depending on the temperature of the electrode slurry, the central portion and both side portions show different degrees of thermal expansion due to a structural difference. By inducing deformation of the coating roll to correspond to the deformation of the discharge portion of the electrode slurry slot die, the distance between the discharge portion of the electrode slurry slot die and the current collector layer carried by the coating roll is uniformly controlled.

The inventors of the present invention confirmed that, through various and repeated experiments and observations, when the temperature of the electrode slurry discharged from the slot die was lower than the reference value (23° C.), both sides of the discharge part contracted to a greater width than the center. . Conversely, when the temperature of the electrode slurry discharged from the slot die was higher than the reference value (23° C.), it was confirmed that both sides of the discharge part expanded to a greater extent in the center.

Specifically, the coating roll is a roller positioned in a region corresponding to the discharge portion of the electrode slurry slot die. That is, the coating roll is located in the region where the electrode slurry is discharged from the electrode slurry slot die. The coating roll may include a cylindrical roller body having a hollow formed therein; a rotating shaft fastened to both side ends of the roller body to support the roller body and to apply a rotational force to the roller body; and a temperature control member positioned inside the roller body to heat or cool the roller body. At this time, when the roller body is divided into peripheral portions on both sides of the center and the center in the width direction, the difference between the outer diameter (C _out ) and the inner diameter (C _in ) of the center (C _out - C _in ) and the outer diameter (S) of the periphery _out ) and the difference of the inner diameter (S _in ) (S _out - S _in ) has a different structure. The coating roll is heated or cooled by the temperature control member located inside the coating roll. If, when heating the coating roll by the temperature control member, the thermal expansion effect is concentrated in the center of the hollow of the roller body, the outer diameter of the coating roll is changed. At this time, the degree of change in the outer diameter of the coating roll can be designed by the difference between the outer diameter and the inner diameter of each area of the roller body.

In one embodiment, the roller body of the coating roll satisfies Equation 1:

[Equation 1]

C _out - C _in > S _out - S _in

In Equation 1, C _out and C _in represent the outer diameter and inner diameter of the center in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral part in the hollow structure, respectively. In a specific example, the roller body has a structure _in which the difference between _{the outer diameter (C out} ) and the inner diameter (C _{in ) of the hollow structure (C out} - C _in ) sequentially or continuously decreases from the center to the periphery. That is, when the roller body is viewed in cross section, it means that the peripheral cross-sectional area is smaller than the central cross-sectional area of the roller body.

In another embodiment, the roller body has a structure that satisfies the following Equation 2:

[Equation 2]

C _out - C _in < S _out - S _in

In Equation 2, C _out and C _in represent the outer diameter and inner diameter of the central portion in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral portion in the hollow structure, respectively. In a specific example, the roller body has a structure _in which the difference between _{the outer diameter (C out} ) and the inner diameter (C _{in ) of the hollow structure (C out} - C _in ) sequentially or continuously increases from the center to the periphery. That is, when the roller body is viewed in cross-section, it means that the peripheral cross-sectional area is larger than the central cross-sectional area of the roller body.

On the other hand, when the coating roll of the electrode slurry coating system according to the present invention is heated by a temperature control member, the thermal expansion effect is concentrated in the center of the hollow of the roller body to change the outer diameter of the coating roll. Conversely, when the coating roll is cooled by the temperature control member, the central portion of the roller body is shrunk to a greater width than the periphery of the roller body, and thus the roller body has a shape that does not interfere with the contraction. In this state, the roller body contracts. However, since both side ends of the roller body are fixed to the rotation shaft, the contraction of the roller body in the corresponding area is inhibited. As a result, the coating roll forms an inverted crown structure with a concave center. On the other hand, when Equation 1 is satisfied in the embodiment of the present invention, since the thickness of the cross-sectional area of the central portion is thicker than the thickness of the cross-sectional area of the peripheral portion, the degree of change in the outer diameter may be greater.

In one embodiment, the electrode slurry coating system according to the present invention includes a temperature sensor for measuring the temperature of the electrode slurry, and a controller for controlling the temperature control member of the coating roll according to the measured value of the temperature sensor. In a specific example, when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the temperature control member heats the coating roll, and the temperature of the electrode slurry measured by the temperature sensor is set to a preset reference temperature When the temperature is lower than the temperature, the temperature control member includes a control unit for controlling to cool the coating roll.

In a specific embodiment, when the coating roll is heated by the temperature control member, the coating roll forms a crown structure. In another specific embodiment, upon cooling of the coating roll by the temperature control member, the coating roll forms an inverted crown structure.

In one embodiment, the temperature control member is a heat medium flow path formed in the width direction of the roller body. In the present invention, by forming the heat medium flow path with the temperature control member, it is possible to control the heating or cooling of the coating roll by setting the temperature of the supplied heat medium to high or low. In this case, heating and cooling of the coating roll may be performed using a single flow path.

In another embodiment, the temperature control member includes a heating coil and a cooling passage. The heating coil heats the coating roll, and the cooling passage cools the coating roll.

In addition, the present invention provides an electrode slurry coating method using the electrode slurry coating system described above. In one embodiment, in the electrode slurry coating method according to the present invention, when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the temperature control member heats the coating roll, and the temperature is measured by the temperature sensor When the temperature of the electrode slurry is lower than a preset reference temperature, the temperature control member controls the coating roll to cool.

Deformation is induced in the discharge portion of the electrode slurry slot die by the temperature of the discharged electrode slurry. In the present invention, the shape of the coating roll is changed to correspond to the deformation of the discharge part of the electrode slurry slot die.

In a specific embodiment, the preset reference temperature described above is in the range of 22 to 24°C, for example, 23°C. When the temperature of the electrode slurry discharged from the slot die is lower than the reference value (23° C.), both sides of the discharge portion are shrunk to a greater width than the central portion. In this case, the coating roll is cooled to form an inverted crown structure. Through this, the gap between the coating part of the electrode slurry slot die and the coating roll is uniformly controlled. Conversely, when the temperature of the electrode slurry discharged from the slot die is higher than the reference value (23° C.), both sides of the discharge portion expand to a greater extent at the center portion. In this case, the coating roll is heated to form a crown structure. Through this, the gap between the coating part of the electrode slurry slot die and the coating roll is uniformly controlled.

In one embodiment, in the electrode slurry coating method according to the present invention, when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the coating roll is heated in the range of 25 to 50° C., and the temperature sensor When the temperature of the electrode slurry measured by is less than the preset reference temperature, the coating roll is cooled in the range of 5 to 20 ℃.

The electrode slurry refers to a composition of a slurry state including an electrode active material. The positive electrode or negative electrode means an electrode for a secondary battery, specifically, an electrode for a lithium secondary battery.

In one example, the electrode means a positive electrode and/or a negative electrode of a lithium secondary battery.

The positive electrode has a structure in which a positive electrode active material layer having a two-layer structure is laminated on a positive electrode current collector. In one example, the positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder polymer, and if necessary, may further include a positive electrode additive commonly used in the art.

The positive active material may be a lithium-containing oxide, and may be the same or different. As the lithium-containing oxide, a lithium-containing transition metal oxide may be used.

For example, the lithium-containing transition metal oxide is Li _x CoO ₂ (0.5<x<1.3), Li _x NiO ₂ (0.5<x<1.3), Li _x MnO ₂ (0.5<x<1.3), Li _x Mn ₂ O ₄ (0.5<x<1.3), Li _x (Ni _a Co _b Mn _c )O ₂ (0.5<x<1.3, 0<a<1, 0<b<1, 0<c<1, a +b+c=1), Li _x Ni _1-y Co _y O ₂ (0.5<x<1.3, 0<y<1), Li _x Co _1-y Mn _y O ₂ (0.5<x<1.3, 0 ≤y<1), Li _x Ni _1-y Mn _y O ₂ (0.5<x<1.3, O≤y<1), Li _x (Ni _a Co _b Mn _c )O ₄ (0.5<x<1.3, 0 <a<2, 0<b<2, 0<c<2, a+b+c=2), Li _x Mn _2-z Ni _z O ₄ (0.5<x<1.3, 0<z<2), Li _x Mn _2-z Co _z O ₄ (0.5<x<1.3, 0<z<2), Li _x CoPO ₄ (0.5<x<1.3) and Li _x FePO ₄ (0.5<x<1.3) It may be any one selected from or a mixture of two or more thereof, and the lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition, in addition to the lithium-containing transition metal oxide, at least one selected from the group consisting of sulfide, selenide, and halide may be used.

The positive active material may be included in the positive active material layer in an amount of 94.0 to 98.5 wt%. When the content of the positive electrode active material satisfies the above range, it is advantageous in terms of manufacturing a high-capacity battery and providing sufficient positive electrode conductivity or adhesion between electrode materials.

The current collector used for the positive electrode is a metal with high conductivity, and any metal that can be easily adhered to the positive electrode active material slurry and has no reactivity in the voltage range of the electrochemical device may be used. Specifically, non-limiting examples of the current collector for the positive electrode include a foil made of aluminum, nickel, or a combination thereof.

The positive active material layer further includes a conductive material. The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive active material. The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the secondary battery. For example, as the conductive material, graphite such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; At least one selected from the group consisting of polyphenylene derivatives and the like may be used.

The negative electrode has a structure in which a negative active material layer having a two-layer structure is laminated on a negative electrode current collector. In one example, the anode active material layer includes an anode active material, a conductive material, a binder polymer, and the like, and if necessary, may further include an anode additive commonly used in the art.

The negative active material may include a carbon material, lithium metal, silicon or tin. When a carbon material is used as the negative electrode active material, both low crystalline carbon and high crystalline carbon may be used. Soft carbon and hard carbon are representative of low crystalline carbon, and natural graphite, Kish graphite, pyrolytic carbon, and liquid crystal pitch-based carbon fiber are representative of high crystalline carbon. (mesophase pitch based carbon fiber), carbon microspheres (mesocarbon microbeads), liquid crystal pitch (Mesophase pitches), and at least one type of high-temperature calcined carbon selected from the group consisting of petroleum and coal-based coke (petroleum orcoal tar pitch derived cokes) is representative to be.

Non-limiting examples of the current collector used for the negative electrode include a foil made of copper, gold, nickel, or a copper alloy, or a combination thereof. In addition, the current collector may be used by stacking substrates made of the above materials.

In addition, the negative electrode may include a conductive material and a binder commonly used in the art.

Hereinafter, the present invention will be described in more detail with reference to the drawings. Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

(First embodiment)

2 is a cross-sectional view of a coating roll applied to an electrode slurry coating system according to an embodiment of the present invention, and FIG. 3 is a right cross-sectional view of a coating roll applied to an electrode slurry coating system according to an embodiment of the present invention. .

2 to 3, the coating roll 100 is a hollow cylindrical roller body 110; It is fastened to both side ends of the roller body 110 , and includes a rotation shaft 130 to support the roller body 110 and apply a rotational force to the roller body 110 . In addition, although not shown in FIG. 2 , a temperature control member including a heat medium flow path is formed inside the coating roll 100 .

On the other hand, when the roller body is divided into the central portion (C) and the peripheral portions (S) on both sides of the central portion in the width direction, the difference between the outer diameter (C _out ) and the inner diameter (C _in ) of the center (C _out - C _in ) And the difference between the outer diameter (S _out ) and the inner diameter (S _{in ) of the periphery (S out} - S _in ) has a different structure.

Specifically, when the cross-section of the roller body 110 is viewed, the cross-sectional thickness (C _out - C _in ) of the central portion (C) may be thicker than the cross-sectional thickness (S _out - S _{in ) of the peripheral portion.} More specifically, the roller body 110 satisfies Equation 1 below.

[Equation 1]

C _out - C _in > S _out - S _in

In Equation 1, C _out and C _in represent the outer diameter and inner diameter of the center in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral part in the hollow structure, respectively.

On the other hand, when the coating roll 100 is heated, the hollow structure inside expands and pushes up the roller body 110 to the outside. Specifically, the center of the roller body 110 is pushed up, and the coating roll 100 forms a crown structure. Conversely, when the coating roll 100 is cooled, the inner hollow structure is contracted while the center of the roller body 110 is watered. In this case, the coating roll 100 forms an inverted crown structure while the rotation shaft 130 fastened to both ends suppresses the contraction of the periphery of the roller body 110 .

(Second embodiment)

4 is a front view of an electrode slurry coating system according to an embodiment of the present invention. 4 is a case in which the temperature of the discharged electrode slurry is 26°C higher than 23°C, which is a design reference value of the electrode slurry slot die 201 . When the temperature of the electrode slurry discharged from the electrode slurry slot die 201 is higher than the reference value (23° C.), both sides of the electrode slurry discharge portion expand to a greater width than the center portion. In this case, the coating roll 200 is heated to 40° C. using a temperature control member. As the coating roll 200 is heated, the inner hollow region expands and pushes up the roller body 210 , and both side ends are fixed to the rotating shaft 230 to suppress the expansion of the roller body 210 . As a result, the roller body 210 forms a crown structure with a convex center. Through this, the distance between the discharge part of the electrode slurry slot die 201 and the coating roll 200 is uniformly controlled.

5 is a result of measuring the temperature distribution and displacement according to the heating of the coating roll. Specifically, FIG. 5 shows the temperature distribution according to the result of heating the coating roll to 40° C. with color. In addition, the lower graph is the result of measuring the displacement in the longitudinal direction when the coating roll is heated.

Referring to FIG. 5 , based on the cross-section of the coating roll, the center is a relatively high temperature and the periphery is a relatively low temperature. At this time, the cylindrical coating roll expands from the center to the periphery (Z direction) based on the circular cross section. When viewed in the longitudinal direction (X direction), the coating roll has a structure in which the central portion expands by about 0.048 mm and the side end expands by about 0.033 mm. As a result, the coating roll forms a crown structure.

(Third embodiment)

6 is a front view of an electrode slurry coating system according to another embodiment of the present invention. 6 is a case in which the temperature of the discharged electrode slurry is 20° C. lower than the 23° C. design reference value of the electrode slurry slot die 301 . When the temperature of the electrode slurry discharged from the electrode slurry slot die 301 is lower than the reference value (23° C.), both sides of the electrode slurry discharge portion are shrunk to a greater extent in the center. In this case, the coating roll 300 is cooled to 10° C. using a temperature control member. As the coating roll 300 cools, the inner hollow member contracts to a greater width without interfering with the contraction of the roller body 210, and both side ends of the roller body 110 are fixed to the rotation shaft 330 to prevent the contraction. is suppressed As a result, the roller body 310 forms an inverted crown structure in which the center C is concave. Through this, the distance between the discharge part of the electrode slurry slot die 301 and the coating roll 300 is uniformly controlled.

7 is a result of measuring the temperature distribution and displacement according to the cooling of the coating roll. Specifically, FIG. 7 shows the result of cooling the coating roll to 10° C., and the temperature distribution according to the color is displayed. In addition, the lower graph is the result of measuring the displacement in the longitudinal direction when the coating roll is cooled.

Referring to FIG. 7 , based on the cross-section of the coating roll, the center is a relatively low temperature and the periphery is a relatively high temperature. At this time, the cylindrical coating roll shrinks from the center to the periphery (Z direction) based on the circular cross section. When viewed in the longitudinal direction (X direction), the coating roll has a structure in which the central portion is shrunk by about 0.038 mm and the side end is shrunk by about 0.025 mm. As a result, the coating roll will form an inverted crown structure.

(Fourth embodiment)

8 is a cross-sectional view of a coating roll applied to the electrode slurry coating system according to another embodiment of the present invention, and FIG. 9 is a right sectional view of the coating roll applied to the electrode slurry coating system according to an embodiment of the present invention. to be.

8 to 9, the coating roll 400 is a hollow cylindrical roller body 410; It is fastened to both side ends of the roller body 410 , and includes a rotation shaft 430 for supporting the roller body 410 and applying a rotational force to the roller body 410 . In addition, although not shown in FIGS. 8 to 9 , a temperature control member including a heat medium flow path is formed inside the coating roll 400 .

On the other hand, when the roller body is divided into the central portion (C) and the peripheral portions (S) on both sides of the central portion in the width direction, the difference between the outer diameter (C _out ) and the inner diameter (C _in ) of the center (C _out - C _in ) And the difference between the outer diameter (S _out ) and the inner diameter (S _{in ) of the periphery (S out} - S _in ) has a different structure.

Specifically, when the cross-section of the roller body 410 is viewed, the cross-sectional thickness (C _out - C _in ) of the central portion (C) may be thinner than the cross-sectional thickness (S _out - S _{in ) of the peripheral portion.} More specifically, the roller body 410 satisfies Equation 2 below.

[Equation 2]

C _out - C _in < S _out - S _in

In Equation 2, C _out and C _in represent the outer diameter and inner diameter of the central portion in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral portion in the hollow structure, respectively.

On the other hand, when the coating roll 400 is heated, the hollow structure inside expands and pushes up the roller body 410 to the outside. Specifically, the center of the roller body 410 is pushed up, and the coating roll 400 forms a crown structure. Conversely, when the coating roll 400 is cooled, the inner hollow structure is contracted and the center of the roller body 410 is watered. In this case, the coating roll 400 forms an inverted crown structure while the rotation shafts 430 fastened to both ends suppress the contraction of the periphery of the roller body 410 .

Above, the present invention has been described in more detail through drawings and examples. However, the configuration described in the drawings or embodiments described in the present specification is only one embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various equivalents and It should be understood that there may be variations.

10, 100, 200, 300, 400: coating roll
20, 201, 301: electrode slurry slot die
21: electrode slurry discharge unit
30: current collector layer
31: electrode slurry coating part
110, 210, 310, 410: roller body
130, 230, 330, 430: axis of rotation
C: central
C _out : the outer diameter of the center
C _in : inner diameter of center
S: periphery
S _out : the outer diameter of the periphery
S _in : the inner diameter of the periphery

Claims (12)

an electrode slurry slot die for discharging electrode slurry;
a coating roll for supporting and transferring the current collector layer;
a current collector layer on which the electrode slurry discharged from the electrode slurry slot die is coated on one side or both sides but transferred along the coating roll; and
A temperature sensor for measuring the temperature of the electrode slurry discharged from the electrode slurry slot die,
The coating roll,
a cylindrical roller body having a hollow formed therein;
a rotating shaft fastened to both side ends of the roller body to support the roller body and to apply a rotational force to the roller body; and
It is located on the inside of the roller body, including a temperature control member for heating or cooling the roller body,
The roller body, when divided into the periphery of both sides of the center and the center based on the width direction, the difference between the outer diameter (C _out ) and the inner diameter (C _in ) of the center (C _out - C _in ) and the outer diameter of the periphery (S _out ) _{and the difference in} inner diameter (S in ) (S _out - S _in ) of an electrode slurry coating system having a different structure.
The method of claim 1,
The roller body is an electrode slurry coating system having a structure that satisfies the following Equation 1:
[Equation 1]
C _out - C _in > S _out - S _in
In Equation 1, C _out and C _in represent the outer diameter and inner diameter of the center in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral part in the hollow structure, respectively.
3. The method of claim 2,
The roller body is an electrode slurry coating system _in which the difference (C _out - C _in ) of the hollow structure from the center to the periphery _{is sequentially or continuously reduced between the outer diameter (C out} ) and the inner diameter (C in).
The method of claim 1,
The roller body is an electrode slurry coating system having a structure satisfying Equation 2:
[Equation 2]
C _out - C _in < S _out - S _in
In Equation 2, C _out and C _in represent the outer diameter and inner diameter of the central portion in the hollow structure, respectively, and S _out and S _in represent the outer diameter and inner diameter of the peripheral portion in the hollow structure, respectively.
5. The method of claim 4,
The roller body is an electrode slurry coating system having a structure _in which the difference (C _out - C _in ) of the hollow structure from the center to the periphery increases the outer diameter (C _out ) and the inner diameter (C in ) sequentially or continuously.
The method of claim 1,
When the coating roll is heated by the temperature control member, the coating roll forms a crown structure,
When the coating roll is cooled by the temperature control member, the coating roll forms an inverted crown structure.
The method of claim 1,
When the temperature of the electrode slurry measured by the temperature sensor exceeds the preset reference temperature, the temperature control member heats the coating roll, and when the temperature of the electrode slurry measured by the temperature sensor is less than the preset reference temperature, the temperature The control member further comprises a control unit for controlling to cool the coating roll electrode slurry coating system.
The method of claim 1,
The temperature control member is an electrode slurry coating system, characterized in that the heat medium flow path formed in the width direction of the roller body.
The method of claim 1,
The temperature control member is an electrode slurry coating system including a heating coil and a cooling passage.
In the electrode slurry coating method using the electrode slurry coating system according to claim 1,
When the temperature of the electrode slurry measured by the temperature sensor exceeds the preset reference temperature, the temperature control member heats the coating roll, and when the temperature of the electrode slurry measured by the temperature sensor is less than the preset reference temperature, the temperature control member An electrode slurry coating method in which a false coating roll is controlled to cool.
11. The method of claim 10,
The preset reference temperature is an electrode slurry coating method, characterized in that it is set within the range of 22 to 24 ℃.
11. The method of claim 10,
When the temperature of the electrode slurry measured by the temperature sensor exceeds the preset reference temperature, heating the coating roll in the range of 25 to 50 ℃,
When the temperature of the electrode slurry measured by the temperature sensor is less than a preset reference temperature, the electrode slurry coating method for cooling the coating roll in the range of 5 to 20 ℃.

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