Electrode slurry coating system and electrode slurry coating method

Abstract

The present invention relates to an electrode slurry coating system capable of controlling the flow rate of electrode slurry and an electrode slurry coating method using the electrode slurry coating system. The loading amount of the electrode slurry can be controlled in response to the temperature of the electrode slurry discharged from the electrode slurry slit die during the electrode slurry coating.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0003160 filed on January 11, 2021, and the entire contents disclosed in the Korean Patent Application are incorporated into this application as a part of this specification.

[0002] The present invention relates to an electrode slurry coating system capable of controlling the flow rate of electrode slurry and an electrode slurry coating method using the electrode slurry coating system. Background Art

[0003] As technology develops and demand for mobile devices increases, demand for secondary batteries is also increasing rapidly. Among secondary batteries, lithium secondary batteries are widely used as energy sources for various electronic products and various mobile devices because of their high energy density, high operating voltage, and excellent retention and life characteristics.

[0004] As the application field of secondary batteries continues to expand, the demand for secondary batteries with higher capacity is rapidly increasing. As a method for increasing the capacity of secondary batteries, the technology of increasing the load of electrode mixture layer is being studied. Electrodes for secondary batteries are manufactured by drying and rolling after coating electrode slurry on current collector. However, in order to increase the load of electrode mixture layer, a large amount of electrode slurry should be coated on current collector. A higher level of coating uniformity is required in order to increase the coating amount of electrode slurry.

[0005] Figure 1 is a diagram showing a conventional electrode manufacturing process. Figure 1 The process of discharging the electrode slurry through the electrode slit die onto the electrode current collector positioned on the coating roller is shown. Figure 1 In the embodiment, the electrode slit die 20 discharges the electrode slurry onto the electrode collector 10, and the electrode collector 10 passes over the coating roller 30 rotating in one direction R. The electrode collector 10 is conveyed in a machine direction (MD) F while passing over the coating roller 30 rotating in one direction R. The electrode slit die 20 discharges and dries the electrode slurry on the electrode collector 10 via the electrode slurry discharging unit 21 to form an electrode mixture layer 11 including the electrode slurry coated to a specific width D on the electrode collector 10.

[0006] Meanwhile, the electrode slurry discharged from the electrode slurry coating die 20 has a temperature variation within a certain range due to variable factors such as heating time or the gradual progress of the process. This temperature variation of the electrode slurry causes a slight displacement or deformation of the electrode slurry discharge unit 21, thereby causing the thickness of the electrode mixture layer 11 to be uneven.

[0007] Figure 2 and Figure 3 is a diagram schematically showing deformation of an electrode slurry slot die according to the temperature of the electrode slurry during conventional electrode manufacturing. Generally, when the temperature of the electrode slurry during electrode manufacturing is lower than the reference temperature (23° C.), the sides of the discharge unit shrink more than the center (see Figure 2 On the other hand, when the temperature of the electrode slurry discharged from the slit die is higher than the reference temperature (23°C), the sides of the discharge unit expand to a greater extent than the center (see Figure 3 ).

[0008] When the shape of the electrode slurry slit die 20 is deformed as described above, the distance between the coating roller 30 and the electrode slurry discharge unit 21 is not constant relative to the transverse direction (TD) of the coating roller. In this case, there is a problem that the load amount of the slurry to be coated on the electrode current collector 10 is also not constant relative to the transverse direction of the coating roller. In particular, when the distance between the electrode slurry discharge unit 21 and the coating roller 30 increases, the load amount of the slurry coated on the electrode current collector 10 increases. Figure 3 , based on the coating roller 30 (along the transverse direction of the coating roller), the slurry loading at the center is greater than the slurry loading on both sides.

[0009] Thus, there is a need for a technology capable of controlling the load amount of electrode slurry discharged from a slot die in response to the temperature of the electrode slurry during coating of the electrode slurry. Summary of the invention

[0010] Technical issues

[0011] The present invention is designed to solve the above-mentioned problems and aims to provide an electrode slurry coating system and an electrode manufacturing method using the electrode slurry coating system, which is capable of controlling the flow rate of electrode slurry discharged from a slit die during electrode slurry coating and is capable of controlling the load amount of the electrode slurry in response to the temperature of the electrode slurry.

[0012] Technical Solution

[0013] The present invention provides an electrode slurry coating system. In one example, the electrode slurry coating system according to the present invention is configured to include: a supply tank configured to supply electrode slurry; a supply pipeline configured to supply the electrode slurry supplied by the supply tank to a manifold of an electrode slurry slit die, wherein the supply pipeline is branched into n (n is an integer greater than or equal to three) supply pipelines in the transverse direction (TD); an electrode slurry slit die configured to discharge the electrode slurry supplied through each of the n supply pipelines; a coating roller configured to support and convey a current collector, the current collector being conveyed along the coating roller by the coating roller and coated with the electrode slurry discharged from the electrode slurry slit die on one side or both sides; and a temperature sensor configured to measure the temperature of the electrode slurry discharged from the electrode slurry slit die. In this case, a control valve is included in each of the n supply pipelines, and the control valve is configured to receive the temperature value of the electrode slurry measured by the temperature sensor and control the flow rate of the electrode slurry.

[0014] In a specific example, when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply lines satisfies the following Formula 1.

[0015] [Formula 1]

[0016] F 中心 <F 侧部

[0017] In formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0018] In another specific example, when the temperature of the electrode slurry measured by the temperature sensor is lower than a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply lines satisfies the following Formula 2.

[0019] [Formula 2]

[0020] F 中心 >F 侧部

[0021] In formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed sub-supply pipeline relative to the lateral direction, F 侧部 Indicates the flow rate of the electrode slurry discharged from the sub-supply line installed at the side with respect to the lateral direction.

[0022] In another example, the electrode slurry slit die in the electrode slurry coating system according to the present invention further includes k (k is an integer greater than or equal to three) distance sensors arranged in the lateral direction in the electrode slurry discharge unit from which the electrode slurry is discharged. In this case, the k distance sensors can measure the gap between the electrode slurry discharge unit and the surface of the coating roller. In addition, the k distance sensors can be arranged in the electrode slurry discharge unit and positioned upstream relative to the traveling direction of the current collector.

[0023] In a specific example, when the gap G is measured by a distance sensor installed at the center of the slurry discharge unit with respect to the lateral direction, 中心 Greater than the gap G measured by the distance sensor installed on the side of the slurry discharge unit 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply pipelines satisfies the following formula 1.

[0024] [Formula 1]

[0025] F 中心 <F 侧部

[0026] In formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0027] In another specific example, when the gap G measured by the distance sensor installed at the center of the slurry discharge unit with respect to the lateral direction is 中心 Smaller than the gap G measured by the distance sensor installed on the side of the slurry discharge unit 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply pipelines satisfies the following formula 2.

[0028] [Formula 2]

[0029] F 中心 >F 侧部

[0030] In formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0031] In one example, each of the n supply lines of the electrode slurry coating system according to the present invention has the following structure: a single line extends from a supply tank and branches into a plurality of sub-supply lines and is coupled to a manifold of an electrode slurry slot die. In addition, the supply line may include at least one pump configured to pump the electrode slurry from the supply tank to the electrode slurry slot die.

[0032] In addition, the present invention provides an electrode slurry coating method using the electrode slurry coating system described above. In one example, the electrode slurry coating method according to the present invention controls the flow rate of the electrode slurry supplied through each of the n supply lines according to the temperature of the electrode slurry measured by the temperature sensor.

[0033] In a specific example, when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies the following Formula 1.

[0034] [Formula 1]

[0035] F 中心 <F 侧部

[0036] In formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0037] In another specific example, when the temperature of the electrode slurry measured by the temperature sensor is lower than a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies the following Formula 2.

[0038] [Formula 2]

[0039] F 中心 >F 侧部

[0040] In formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed sub-supply pipeline relative to the lateral direction, F 侧部 Indicates the flow rate of the electrode slurry discharged from the sub-supply line installed at the side with respect to the lateral direction.

[0041] Meanwhile, in the electrode slurry coating method according to the present invention, the step of controlling the flow rate of the electrode slurry supplied through the supply line includes setting a reference temperature, and the reference temperature may be set within a range of 20°C to 26°C.

[0042] Beneficial Effects

[0043] By utilizing the electrode slurry coating system capable of controlling the flow rate of electrode slurry and the electrode slurry coating method using the electrode slurry coating system according to the present invention, the load amount of the electrode slurry can be easily controlled by controlling the flow rate of the electrode slurry supplied to the supply pipeline in each area in response to the temperature of the electrode slurry discharged from the slit die during electrode slurry coating.

[0044] Therefore, the present invention has the advantage that uniform electrode slurry coating can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The figure illustrates a process of discharging electrode slurry onto an electrode current collector on a coating roller through an electrode slurry slot die according to a conventional method.

[0046] Figure 2 and Figure 3 is a diagram schematically showing deformation of an electrode slit die according to the temperature of an electrode slurry during conventional electrode manufacturing.

[0047] Figure 4 is a schematic diagram illustrating an electrode slurry coating system according to an embodiment of the present invention.

[0048] Figure 5 is a front view of an electrode slurry coating system according to one embodiment of the present invention.

[0049] Figure 6 is a front view of an electrode slurry coating system according to another embodiment of the present invention.

[0050] Figure 7 is a front view of an electrode slurry coating system according to yet another embodiment of the present invention. DETAILED DESCRIPTION

[0051] Hereinafter, the present invention will be described in detail. Prior to this, the terms and words used in this specification and claims should not be interpreted as their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts consistent with the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to best explain his or her invention.

[0052] The present invention provides an electrode slurry coating system capable of controlling the flow rate of electrode slurry. In one example, an electrode slurry coating system according to the present invention includes: a supply tank configured to supply electrode slurry; a supply pipeline configured to supply the electrode slurry supplied by the supply tank to a manifold of an electrode slurry slot die, wherein the supply pipeline is branched into n (n is an integer greater than or equal to three) supply pipelines in a lateral direction; an electrode slurry slot die configured to discharge the electrode slurry supplied through the supply pipeline; a coating roller configured to support and convey a current collector layer; the current collector layer is conveyed along the coating roller and coated with the electrode slurry discharged from the electrode slurry slot die on one side or both sides; and a temperature sensor configured to measure the temperature of the electrode slurry discharged from the electrode slurry slot die.

[0053] Particularly, a control valve is included in each supply line, and the control valve is configured to receive a temperature value of the electrode slurry measured by a temperature sensor and control a flow rate of the electrode slurry.

[0054] According to the present invention, it has been determined that the electrode slurry discharge unit from which the electrode slurry is discharged is displaced or deformed according to the temperature of the electrode slurry discharged from the electrode slurry slit die. In this case, the load amount of the electrode slurry coated on the current collector is also not constant relative to the lateral direction. In particular, when the distance between the electrode slurry discharge unit and the coating roller is greater than the reference distance, the load amount of the electrode slurry in the corresponding area exceeds the reference value, and when the distance between the electrode slurry discharge unit and the coating roller is less than the reference distance, the load amount of the electrode slurry in the area is less than the reference value. Accordingly, the present invention controls the flow rate of the electrode slurry supplied to the corresponding area according to the temperature of the electrode slurry to correspond to the displacement or deformation of the electrode slurry discharge unit.

[0055] Specifically, the electrode slurry slit die is designed based on a situation where the temperature of the electrode slurry is a specific temperature (e.g., 23°C). However, in actual processes, the discharge temperature of the electrode slurry varies in a range of, for example, 20°C to 26°C. This change in the discharge temperature of the electrode slurry causes a slight deformation or displacement of the discharge unit of the electrode slurry slit die. More specifically, depending on the temperature of the electrode slurry, the electrode slurry discharge unit of the electrode slurry slit die shows different degrees of thermal expansion due to the structural difference between the center and the two sides. Moreover, the load of the electrode slurry coated on the current collector based on the lateral direction varies according to the thermal expansion of the center and the two sides in the electrode slurry discharge unit. For example, when the temperature of the electrode slurry is designed based on the situation of 23°C and the discharge temperature of the electrode slurry exceeds 23°C, the electrode slurry slit die thermally expands on both sides. In addition, the space between the coating roller and the two sides of the electrode slurry slit die is reduced, so that the electrode slurry load at the center in the lateral direction is greater than that on the two sides. Accordingly, the electrode slurry coating system according to the present invention includes an electrode slurry slit die and a control valve, the electrode slurry slit die is connected in the lateral direction with a supply line branched into n (n is 3 or more) supply lines, and the control valve is capable of controlling the flow rate in each supply line according to the slurry temperature. Here, n can be selected in the range of 3 to 50, 3 to 25, 3 to 15, or 3 to 9. According to the present invention, by controlling the flow rate of the electrode slurry supplied to the supply line of each area in response to the temperature of the electrode slurry discharged from the electrode slurry slit die during electrode slurry coating, the load of the electrode slurry can be easily controlled.

[0056] The inventors of the present invention have confirmed through various and repeated tests and observations that when the temperature of the electrode slurry discharged from the electrode slurry slot die is lower than a reference value, the two sides of the discharge unit shrink more than the center. Conversely, the inventors of the present invention have confirmed that when the temperature of the electrode slurry discharged from the electrode slurry slot die is higher than a reference value, the two sides of the discharge unit expand more than the center.

[0057] In the present invention, the term "center" refers to the center point based on the length in the transverse direction or width direction of the electrode slurry slit die. In addition, the term "side" refers to the point corresponding to 10% and / or 90% based on the length in the transverse direction or width direction of the electrode slurry slit die or the coating roller. For example, the gap or temperature of the "side" of the coating roller represents the average of the values ​​measured at 10% and 90% based on the length in the transverse direction or width direction of the coating roller.

[0058] In a specific example, the electrode slurry coating system according to the present invention controls the control valve so that when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the flow rate of the electrode slurry supplied through each supply line satisfies the following Formula 1.

[0059] [Formula 1]

[0060] F 中心 <F 侧部

[0061] In formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0062] Meanwhile, the flow rates of the control valves installed at the center and the side can be controlled within 10%. However, the present invention is not limited thereto. In addition, the control valve is controlled so that the flow rate at the side of the electrode slurry slot die relative to the lateral direction is greater than the flow rate at the center, but when the number of supply lines exceeds three, the control valve can be controlled so that the flow rate increases sequentially or gradually from the center to the side.

[0063] In another specific example, when the temperature of the electrode slurry measured by the temperature sensor is lower than a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies the following Formula 2.

[0064] [Formula 2]

[0065] F 中心 >F 侧部

[0066] In formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed sub-supply pipeline relative to the lateral direction, F 侧部 Indicates the flow rate of the electrode slurry discharged from the sub-supply line installed at the side with respect to the lateral direction.

[0067] Even in this case, the flow rates of the control valves installed at the center and the side can be controlled within 10%. However, the present invention is not limited thereto. In addition, the control valve is controlled so that the flow rate at the center of the electrode slurry slit die relative to the lateral direction is greater than the flow rate at the side, but when the number of supply lines exceeds three, the control valve may be controlled so that the flow rate increases sequentially or gradually from the side to the center.

[0068] In another example, the electrode slurry slot die in the electrode slurry coating system according to the present invention further includes k (k is an integer greater than or equal to three) distance sensors, which are arranged in the lateral direction in the electrode slurry discharge unit from which the electrode slurry is discharged. In this case, the distance sensor measures the distance between the electrode slurry discharge unit and the surface of the coating roller. The number of multiple distance sensors may correspond to the number of branched supply lines, and the multiple distance sensors may be positioned at the same height.

[0069] In addition, a plurality of distance sensors may be arranged in the electrode slurry discharge unit and positioned upstream relative to the traveling direction of the electrode current collector. The area of ​​the electrode current collector not coated with the electrode slurry may be referred to as the upstream direction. Meanwhile, the distance sensor may be an infrared or ultrasonic distance sensor that measures the distance between the measuring area and the coating roller.

[0070] Specifically, when the gap G measured by the distance sensor installed at the center of the slurry discharge unit with respect to the lateral direction 中心 Greater than the gap G measured by the distance sensor installed on the side of the slurry discharge unit 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies the following formula 1.

[0071] [Formula 1]

[0072] F 中心 <F 侧部

[0073] In formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0074] Alternatively, when the gap G is measured by a distance sensor installed at the center of the slurry discharge unit with respect to the lateral direction 中心 Smaller than the gap G measured by the distance sensor installed on the side of the slurry discharge unit 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply pipeline satisfies Formula 2.

[0075] [Formula 2]

[0076] F 中心 >F 侧部

[0077] In formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed sub-supply pipeline relative to the lateral direction, F 侧部 Indicates the flow rate of the electrode slurry discharged from the sub-supply line installed at the side with respect to the lateral direction.

[0078] The flow rate of the control valves installed in the center and the side can be controlled within 10%. However, the present invention is not limited thereto. Accordingly, according to the present invention, the difference in the electrode slurry loading in the width direction can be controlled to be 5 (mg / 25cm 2 ) or smaller.

[0079] In addition, the present invention provides an electrode slurry coating method using the electrode slurry coating system described above. In one example, the electrode slurry coating method according to the present invention controls the flow rate of the electrode slurry supplied through each supply line according to the temperature of the electrode slurry measured by 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 control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies the above formula 1.

[0080] Alternatively, when the temperature of the electrode slurry measured by the temperature sensor is lower than a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies the above-mentioned Formula 2.

[0081] In a specific example, the preset reference temperature is in the range of 22°C to 24°C, for example, 23°C. When the temperature of the electrode slurry discharged from the slit die is lower than the reference value (23°C), the two sides of the discharge unit shrink more than the center. Moreover, the gap between the coating roller and the center of the electrode slurry slit die is reduced, so that the electrode slurry load on the two sides in the lateral direction is greater than the electrode slurry load in the center. Therefore, the present invention controls the flow of the control valve located in each area. For example, when the electrode slurry is supplied, the flow rate in the center is greater than the flow rate in the lateral direction. On the other hand, when the temperature of the electrode slurry discharged from the slit die is higher than the reference value (23°C), the discharge unit expands more at the two sides than at the center. In this case, when the electrode slurry is supplied, the flow rate at the side is greater than the flow rate at the center relative to the lateral direction.

[0082] In one example, the preset reference temperature may be set in the range of 20° C. to 26° C. In a specific example, the preset reference temperature is in the range of 22° C. to 24° C., for example, 23° C.

[0083] In a specific example, the electrode to be manufactured in the present invention is an electrode for a pouch-type secondary battery. In addition, the electrode slurry generally refers to a composition in a slurry state including an electrode active material, and the positive electrode or negative electrode refers to an electrode for a secondary battery, and in particular, an electrode for a lithium secondary battery.

[0084] In one example, the electrode refers to a positive electrode and / or a negative electrode of a lithium secondary battery.

[0085] The positive electrode has a structure in which a positive electrode active material layer having a two-layer structure is stacked on a positive electrode current collector. In one example, the positive electrode active material layer includes a positive electrode active material, a conductive material, a binder polymer, etc., and if necessary, may further include a positive electrode additive commonly used in the art.

[0086] The positive electrode active material may be a lithium-containing oxide and may be the same or different. A lithium-containing transition metal oxide may be used as the lithium-containing oxide.

[0087] For example, the lithium-containing transition metal oxide may be any one selected from the group consisting of: Li x CoO2 (0.5 < x < 1.3), Li x NiO2 (0.5 < x < 1.3), Li x MnO2 (0.5 < x < 1.3), Li x Mn2O4 (0.5 < x < 1.3), Li x (Ni a Co b Mn c )O2 (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 O2 (0.5 < x < 1.3, 0 < y < 1), Li x Co 1-y Mn y O2 (0.5 < x < 1.3, 0 ≤ y < 1), Li x Ni 1-y Mn y O2 (0.5 < x < 1.3, 0 ≤ y < 1), Li x (Ni a Co b Mn c )O4 (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 O4 (0.5 < x < 1.3, 0 < z < 2), Li x Mn 2- z Co z O4 (0.5 < x < 1.3, 0 < z < 2), Li x CoPO4 (0.5 < x < 1.3), and Li x FePO4 (0.5 < x < 1.3) and mixtures of two or more of the above substances. The lithium-containing transition metal oxide may be coated with a metal or metal oxide such as aluminum (Al). In addition, in addition to the lithium-containing transition metal oxide, at least one selected from the group consisting of sulfides, selenides, and halides may be used.

[0088] The positive electrode active material layer may contain 94.0 wt % to 98.5 wt % of the positive electrode active material. When the content of the positive electrode active material satisfies the above range, it is advantageous in manufacturing a high capacity battery and providing sufficient positive electrode conductivity or adhesion between electrode materials.

[0089] The current collector for the positive electrode is a metal with high electrical conductivity, and any metal that can easily adhere to the positive electrode active material slurry and is not reactive in the voltage range of the electrochemical device can be used. Specifically, non-limiting examples of the current collector for the positive electrode include foils made of aluminum, nickel, or a combination thereof.

[0090] The positive electrode active material layer further includes a conductive material. A conductive material in the range of 1 wt % to 30 wt % is generally added relative to the total weight of the mixture containing the positive electrode material. The conductive material is not particularly limited as long as it has conductivity and does not cause chemical changes in the secondary battery. For example, at least one selected from the group consisting of the following materials can be used as a 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 whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and polyphenylene derivatives.

[0091] The negative electrode has a structure in which a negative electrode active material having a two-layer structure is stacked on a negative electrode current collector. In one example, the negative electrode active material layer includes a negative electrode active material, a conductive material, a binder polymer, etc., and if necessary, may further include a negative electrode additive commonly used in the art.

[0092] The negative electrode additive may include a carbon material, lithium metal, silicon or tin. When the carbon material is used as the negative electrode active material, both low crystalline carbon and high crystalline carbon can be used. Soft carbon and hard carbon are representatives of low crystalline carbon, and at least one type of high temperature roasted carbon selected from the group consisting of natural graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesophase microbeads, mesophase pitch, and coke derived from petroleum or coal tar pitch is a representative of high crystalline carbon.

[0093] Non-limiting examples of the current collector for the negative electrode include foils made of copper, gold, nickel, copper alloys, or a combination of the foregoing materials. In addition, the current collector may be used by stacking substrates made of the foregoing materials.

[0094] In addition, the negative electrode may include a conductive material and a binder commonly used in the art.

[0095] Mode for Carrying Out the Invention

[0096] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. The present invention can be modified in many aspects and can have several forms, and specific embodiments will be shown in the accompanying drawings and described in detail below. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that the present invention includes any modifications, equivalents and substitutes included in the spirit and scope of the present invention.

[0097] (First Embodiment)

[0098] Figure 4 is a schematic diagram showing an electrode slurry coating system according to an embodiment of the present invention.

[0099] Reference Figure 4 , the electrode slurry coating system 100 according to the present invention includes: a supply tank 110, configured to supply electrode slurry; a supply line 130, configured to supply the electrode slurry supplied by the supply tank 110 to the manifold side 121 of the electrode slurry slot die 120, the supply line 130 branching into n (n is an integer greater than or equal to three) supply lines in the lateral direction; the electrode slurry slot die 120, configured to discharge the electrode slurry supplied through the supply line 130; a coating roller 140, configured to support and convey the current collector layer 150; the current collector layer 150, conveyed along the coating roller 140 and coated with the electrode slurry discharged from the electrode slurry slot die 120 on one side or both sides; and a temperature sensor 160, configured to measure the temperature of the electrode slurry discharged from the electrode slurry slot die 120. Specifically, the temperature sensor 160 is a non-contact temperature sensor. The temperature sensor 160 can measure the temperature of the discharged electrode slurry in a non-contact manner in real time. For example, the temperature sensor 160 measures the temperature of the discharged electrode slurry continuously or at regular intervals. A commercially available infrared temperature sensor or a thermal imaging camera may be used as the temperature sensor 160.

[0100] At this time, the supply line 130 includes a control valve 133, which is used to receive the temperature value of the electrode slurry measured by the temperature sensor 160 and control the flow rate of the electrode slurry. Figure 4 In the embodiment, the supply line 130 has a structure in which a single line 131 extends from the supply tank 110 and branches into n sub-supply lines 132, but the present invention is not limited thereto. In this case, the supply line 130 may have a structure in which a single line 131 extends from the supply tank 110, and may have a structure in which the single line 131 branches into n sub-supply lines 132 and is coupled to the manifold 121 of the electrode slurry slot die 120.

[0101] In addition, the supply line 130 includes at least one pump 134 for pumping the electrode slurry from the supply tank 110 to the electrode slurry slot die 120 .

[0102] Meanwhile, a control valve 133 may be installed at each of the n supply lines 130 or the sub-supply lines 132 having a structure branched in a lateral direction of the electrode slurry slot die to individually control the flow rate of the electrode slurry supplied through the corresponding supply lines 130. Figure 4 , it is shown that the supply line 132 is branched into five sub-supply lines, but the present invention is not limited thereto. Also, each control valve 133 receives the temperature value of the electrode slurry measured by the temperature sensor 160 and controls the flow rate of the electrode slurry in each section.

[0103] (Second Embodiment)

[0104] Figure 5 is a front view of an electrode slurry coating system according to an embodiment of the present invention. Figure 5 This is a case where the temperature of the discharged electrode slurry is 26° C., which is higher than the preset reference value, i.e., 23° C., of the electrode slurry slot die 220. When the temperature of the electrode slurry discharged from the electrode slurry slot die 220 is higher than the preset reference value (23° C.), both sides of the electrode slurry discharge unit 222 expand more than the center.

[0105] In this case, the distance between the electrode slurry slit die 220 and the coating roller 240 at the center of the electrode slurry slit die 220 is greater than that at the side of the electrode slurry slit die 220 relative to the transverse direction, so the slurry load at the center of the current collector layer is greater than that at the side relative to the transverse direction. In order to prevent this phenomenon, according to the present invention, the flow rate of the electrode slurry supplied through the supply line of the corresponding area is controlled by controlling the control valve installed at the supply line of each area. Specifically, the control valve is controlled so that the flow rate of the electrode slurry supplied through the corresponding supply line satisfies the following formula 1.

[0106] [Formula 1]

[0107] F 中心 <F 侧部

[0108] In formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0109] The flow rate of the control valve installed in the center and the side can be controlled within 10%. However, the present invention is not limited to this. In addition, the control valve is controlled so that the flow rate at the side of the electrode slurry slot die 220 relative to the lateral direction is greater than the flow rate at the center, but the control valve can be controlled so that the flow rate increases sequentially or gradually from the center to the side.

[0110] (Third Embodiment)

[0111] Figure 6 is a front view of an electrode slurry coating system according to another embodiment of the present invention.

[0112] Figure 6 This is a case where the temperature of the discharged electrode slurry is 20° C., which is lower than the reference value, i.e., 23° C., of the electrode slurry slot die 320. When the temperature of the electrode slurry discharged from the electrode slurry slot die 320 is lower than the reference value (23° C.), both sides of the electrode slurry discharge unit shrink more than the center.

[0113] In this case, the distance between the electrode slurry slit die 320 and the coating roller 340 at the side of the electrode slurry slit die 320 is greater than that at the center of the electrode slurry slit die 320 relative to the lateral direction, so the slurry loading amount at the side of the current collector layer is greater than the slurry loading amount at the center relative to the lateral direction. In order to prevent this phenomenon, according to the present invention, the flow rate of the electrode slurry supplied through the supply line of the corresponding area is controlled by controlling the control valve installed at the supply line of each area. Specifically, the control valve is controlled so that the flow rate of the electrode slurry supplied through the corresponding supply line satisfies the following formula 2.

[0114] [Formula 2]

[0115] F 中心 >F 侧部

[0116] In formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0117] The flow rate of the control valve installed in the center and the side can be controlled within 10%. However, the present invention is not limited to this. In addition, the control valve is controlled so that the flow rate at the center of the electrode slurry slot die 320 relative to the lateral direction is greater than the flow rate at the side, but the control valve can be controlled so that the flow rate increases sequentially or gradually from the side to the center.

[0118] (Fourth Embodiment)

[0119] Figure 7 is a front view of an electrode slurry coating system according to yet another embodiment of the present invention.

[0120] Reference Figure 7, the electrode slurry slot die 420 in the electrode slurry coating system 400 according to the present invention further includes k (k is an integer greater than or equal to three) distance sensors 470 arranged in the lateral direction in the electrode slurry discharge unit 422 from which the electrode slurry is discharged. In this case, the k distance sensors 470 measure the gap between the electrode slurry discharge unit 422 and the coating roller 440. Although in Figure 7 Although not shown in FIG. 4 , the number of k distance sensors 470 may correspond to the number of branched supply lines, and these distance sensors may be positioned at the same height.

[0121] In addition, a plurality of distance sensors 470 may be arranged in the electrode slurry discharge unit 422 and positioned upstream relative to the traveling direction of the current collector. In the figure, the region of the electrode current collector 450 that is not coated with the electrode slurry may be referred to as the upstream direction. Meanwhile, the distance sensor 470 may be an infrared or ultrasonic distance sensor that measures the distance between the measuring region and the coating roller 440.

[0122] Specifically, when the gap G measured by the distance sensor 470 installed at the center of the slurry discharge unit 422 with respect to the lateral direction 中心 is greater than the gap G measured by the distance sensor 470 installed at the side of the slurry discharge unit 422 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies the following formula 1.

[0123] [Formula 1]

[0124] F 中心 <F 侧部

[0125] In formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0126] Alternatively, when the gap G measured by the distance sensor installed at the center of the slurry discharge unit with respect to the lateral direction is 中心 Smaller than the gap G measured by the distance sensor installed on the side of the slurry discharge unit 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through each supply line satisfies Formula 2.

[0127] [Formula 2]

[0128] F 中心 >F 侧部

[0129] In formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

[0130] The flow rate of the control valve 433 installed at the center and the side can be controlled within 10%. However, the present invention is not limited thereto. Accordingly, according to the present invention, the difference in the electrode slurry loading in the width direction can be controlled to be 5 (mg / 25cm 2 ) or smaller.

[0131] The present invention has been described in more detail above through the drawings and embodiments. However, the configurations shown in the drawings or embodiments of this specification are only embodiments of the present invention and do not represent all the technical spirits of the present invention. Therefore, it should be understood that various equivalents and modifications that can replace these configurations may be available at the time of submission.

[0132] [Explanation of Reference Numerals]

[0133] 10: Electrode current collector

[0134] 11: Electrode mixture layer

[0135] 20: Electrode slurry slot die

[0136] 21: Electrode slurry discharge unit

[0137] 30: coating roller

[0138] 100, 200, 300: Electrode slurry coating system

[0139] 110: Supply tank

[0140] 120, 220, 320: electrode slurry slot die

[0141] 121: Manifold

[0142] 122, 422: Electrode slurry discharge unit

[0143] 130: Supply pipeline

[0144] 131: Single pipeline

[0145] 132: Sub-supply pipeline

[0146] 133, 433: Control valve

[0147] 140, 240, 340, 440: coating roller

[0148] 150, 450: Electrode current collector

[0149] 160: Temperature sensor

[0150] 470: Distance sensor

Claims

1. An electrode slurry coating system, comprising: a supply tank configured to supply electrode slurry; a supply line configured to supply the electrode slurry supplied from the supply tank to a manifold of an electrode slurry slot die, the supply line branching into n supply lines in a lateral direction, n being an integer greater than or equal to three; an electrode slurry slit die configured to discharge the electrode slurry supplied through the supply line; a coating roller configured to support and transport a current collector, the current collector being transported by the coating roller and having one or both sides coated with the electrode slurry discharged from the electrode slurry slit die; and a temperature sensor configured to measure the temperature of the electrode slurry discharged from the electrode slurry slot die, Each of the n supply lines includes a control valve configured to receive a temperature value of the electrode slurry measured by the temperature sensor and control a flow rate of the electrode slurry.

2. The electrode slurry coating system according to claim 1, wherein when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply lines satisfies the following formula 1: [Formula 1] F 中心 <F 侧部 In Formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line with respect to the transverse direction, F 侧部 It represents the flow rate of the electrode slurry discharged from the supply line installed at the side with respect to the transverse direction.

3. The electrode slurry coating system according to claim 1, wherein when the temperature of the electrode slurry measured by the temperature sensor is lower than a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply lines satisfies the following formula 2: [Formula 2] F 中心 >F 侧部 In Formula 2, F 中心 represents the flow rate of the electrode slurry discharged from the centrally installed sub-supply pipeline with respect to the transverse direction, F 侧部 It represents the flow rate of the electrode slurry discharged from the sub-supply line installed at the side with respect to the lateral direction.

4. The electrode slurry coating system according to claim 1, wherein The electrode slurry slot die further includes k distance sensors arranged in the transverse direction in an electrode slurry discharge unit from which the electrode slurry is discharged, wherein k is an integer greater than or equal to three, and Each of the k distance sensors measures a gap between the electrode slurry discharge unit and a surface of the coating roller. 5 . The electrode slurry coating system of claim 4 , wherein the k distance sensors are arranged in the electrode slurry discharge unit and positioned upstream with respect to a traveling direction of the current collector.

6. The electrode slurry coating system of claim 4, wherein when the gap G measured by the distance sensor installed at the center of the slurry discharge unit with respect to the lateral direction is 中心 Greater than the gap G measured by the distance sensor installed on the side of the slurry discharge unit 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through the supply pipeline satisfies the following formula 1: [Formula 1] F 中心 <F 侧部 In Formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line with respect to the transverse direction, F 侧部 represents the flow rate of the electrode slurry discharged from each of the n supply lines installed at the side with respect to the lateral direction.

7. The electrode slurry coating system of claim 4, wherein when the gap G measured by the distance sensor installed at the center of the slurry discharge unit with respect to the lateral direction is 中心 Smaller than the gap G measured by the distance sensor installed on the side of the slurry discharge unit 侧部 When , the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply pipelines satisfies the following formula 2: [Formula 2] F 中心 >F 侧部 In Formula 2, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line with respect to the transverse direction, F 侧部 It represents the flow rate of the electrode slurry discharged from the supply line installed at the side with respect to the transverse direction.

8. The electrode slurry coating system of claim 1, wherein each of the n supply lines has a structure in which a single line extends from the supply tank and branches into a plurality of sub-supply lines and is coupled to the manifold of the electrode slurry slot die.

9. The electrode slurry coating system of claim 1, wherein each of the n supply lines comprises at least one pump configured to pump the electrode slurry from the supply tank to the electrode slurry slot die.

10. An electrode slurry coating method using the electrode slurry coating system of claim 1, comprising controlling a flow rate of the electrode slurry supplied through each of the n supply lines according to a temperature of the electrode slurry measured by a temperature sensor.

11. The electrode slurry coating method according to claim 10, wherein when the temperature of the electrode slurry measured by the temperature sensor exceeds a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply lines satisfies the following formula 1: [Formula 1] F 中心 <F 侧部 In Formula 1, F 中心 represents the flow rate of electrode slurry discharged from the centrally installed supply line relative to the lateral direction, F 侧部 Indicates the flow rate of electrode slurry discharged from the supply line installed at the side with respect to the lateral direction.

12. The electrode slurry coating method according to claim 10, wherein when the temperature of the electrode slurry measured by the temperature sensor is lower than a preset reference temperature, the control valve is controlled so that the flow rate of the electrode slurry supplied through each of the n supply lines satisfies the following formula 2: [Formula 2] F 中心 >F 侧部 In Formula 2, F 中心 represents the flow rate of the electrode slurry discharged from the centrally installed sub-supply pipeline with respect to the transverse direction, F 侧部 It represents the flow rate of the electrode slurry discharged from the sub-supply line installed at the side with respect to the lateral direction.

13. The electrode slurry coating method of claim 10, wherein the step of controlling the flow rate of the electrode slurry supplied through each of the n supply lines comprises setting a reference temperature, and the reference temperature is within a range of 20°C to 26°C.

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