Electrode drying degree measuring device and electrode coating apparatus including the same

Abstract

Some embodiments of the electrode drying degree measuring device are configured to measure the degree of drying of the center and side portions of the active material layer dried by the top surface drying device, which is positioned behind the top surface drying device, with reference to the machine direction (MD) of the current collector, with reference to the machine direction of the current collector. Some embodiments of the present invention enable the quantification of the degree of drying of the active material layer of the top surface coated electrode and to derive a correlation between the process variables of the top surface coating device and the top surface drying device and the degree of drying of the active material layer of the top surface coated electrode. Some embodiments of the present invention enable a rapid response when the drying of the active material layer of the top surface coated electrode is not properly performed and can prevent contamination of rollers located in front of the top surface drying device with reference to the machine direction of the current collector and / or rollers facing the back surface coating device.

Description

[Technical Field]

[0001] This disclosure claims priority rights based on Korean Patent Application No. 10-2024-0047177 dated 8 April 2024, and all contents of Korean Patent Application No. 10-2024-0047177 are incorporated by reference into this disclosure.

[0002] The present invention relates to an electrode drying degree measuring device and an electrode coating device including the same. [Background technology]

[0003] In recent years, there has been growing interest in rechargeable batteries that can be used repeatedly for extended periods through recharging, as a way to reduce carbon emissions while decreasing reliance on fossil fuels. In particular, lithium-ion batteries, which use lithium ions as their energy source, have excellent energy density and lifespan, and research and development on them are actively underway. As a result, lithium-ion batteries are used in a variety of fields, including portable electronic devices, vehicles, and ESSs (Energy Storage Systems).

[0004] Generally, the electrodes of lithium secondary batteries are double-sided coated electrodes, where the active material layer is located on both sides of the current collector. The manufacturing process of a conventional double-sided coated electrode is explained below with reference to Figure 1. However, the number and arrangement of rollers shown in Figure 1 are arbitrarily determined for the sake of explanation.

[0005] The current collector B is transported by rollers R1 to R11, and the top surface coating device C1 coats the top surface of the current collector B with a first slurry S1 containing active material, binder, conductive material, and solvent. The top surface drying device D1 dries the first slurry S1 and evaporates the solvent. The top surface coated electrode produced in this way is transported by rollers R1 to R11, and the back surface coating device C2 coats the back surface of the current collector B with a second slurry S2 containing active material, binder, conductive material, and solvent. The back surface drying device D2 dries the second slurry S2 and evaporates the solvent. Subsequently, a double-sided coated electrode is produced through processes such as rolling, slitting, and vacuum drying.

[0006] As mentioned above, conventionally, there was no device to measure the degree of drying of the first active material layer A1 behind the top surface drying device D1, using the machine direction (MD) of the current collector B as a reference. Conventionally, only the loading level of the active material within the first active material layer A1 was measured from the color map of the first active material layer A1.

[0007] Therefore, conventionally, it was not possible to quantify the degree of drying of the first active material layer A1, and it was difficult to derive a correlation between the process variables of the top surface coating apparatus C1 and the top surface drying apparatus D1 and the degree of drying of the first active material layer A1.

[0008] Furthermore, conventionally, if the first active material layer A1 was not properly dried, rollers R5 to R11 located behind the top surface drying device D1, relative to the machine direction (MD) of the current collector B, would become contaminated. This resulted in a decrease in the quality and production yield of the double-sided coated electrodes, ultimately leading to a decline in cell performance. This problem is particularly pronounced when roller R8, which faces the back surface coating device C2, becomes contaminated. [Overview of the project] [Problems that the invention aims to solve]

[0009] The technical concept of this invention aims to solve the problem of quantifying the degree of drying of the active material layer of the top surface coated electrode, and deriving a correlation between the process variables of the top surface coating apparatus and the top surface drying apparatus and the degree of drying of the active material layer of the top surface coated electrode.

[0010] Another problem that the technical concept of the present invention aims to solve is to enable a rapid response when the active material layer of the top surface coated electrode is not properly dried, and to prevent contamination of rollers located in front of the back surface coating device and / or rollers facing the back surface coating device with respect to the mechanical direction (MD) of the current collector. [Means for solving the problem]

[0011] Some embodiments of the present invention that can solve the aforementioned problems are as follows.

[0012] In some embodiments, the electrode drying degree measuring device is positioned behind the top surface drying device, which is configured to dry a slurry coated on the top surface of the current collector, with reference to the machine direction (MD) of the current collector, and can be configured to measure the drying degree of the center and side portions of the active material layer dried by the top surface drying device, respectively.

[0013] In some embodiments, the electrode dryness measurement device can be configured to measure the dryness of the center portion of the active material layer from the brightness of the center portion of the active material layer, and to measure the dryness of the side portion of the active material layer from the brightness of the side portion of the active material layer.

[0014] In some embodiments, the electrode drying degree measuring device can include an image sensor configured to calculate the brightness of the center portion and the side portion of the active material layer from an image of the active material layer.

[0015] In some embodiments, the electrode drying degree measuring device can include an optical sensor configured to irradiate light on the active material layer and analyze the light reflected from the active material layer to calculate the brightness of the center portion and the side portion of the active material layer respectively.

[0016] In some embodiments, the electrode drying degree measuring device can include a transmitting unit configured to transmit a defective signal to a display device when the brightness of the center portion of the active material layer is lower than a reference value or the brightness of the side portion of the active material layer is higher than the reference value.

[0017] In some embodiments, the electrode drying degree measuring device can include a transmitting unit configured to transmit a defective signal to a control device when the brightness of the center portion of the active material layer is lower than an undried reference value or the brightness of the side portion of the active material layer is higher than an over-dried reference value.

[0018] An electrode coating device according to some embodiments can include a top surface drying device configured to dry a first slurry coated on the top surface of a current collector, a back surface coating device configured to coat a second slurry on the back surface of the current collector, and the electrode drying degree measuring device positioned between the top surface drying device and the back surface coating device with reference to the machine direction (MD) of the current collector.

[0019] In some embodiments, the coating device can further include a top surface coating device configured to coat a first slurry on the top surface of the current collector and a back surface drying device configured to dry a second slurry coated on the back surface of the current collector.

Advantages of the Invention

[0020] Some embodiments of the present invention can quantify the drying degree of the active material layer of the top surface coating electrode, and derive the correlation between the process variables of the top surface coating device and the top surface drying device and the drying degree of the active material layer of the top surface coating electrode.

[0021] Some embodiments of the present invention enable a prompt response when the drying of the active material layer of the top surface coating electrode is not properly performed, and prevent the contamination of the roller located in front of the top surface drying device and / or the roller facing the back surface coating device with reference to the machine direction (MD) of the current collector.

[0022] The effects of the embodiments of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly derived and understood by those with ordinary knowledge in the technical field to which the embodiments of the present invention belong from the following description. That is, the unintended effects associated with the implementation of the embodiments of the present invention can also be clearly derived and understood by those with ordinary knowledge in the technical field to which the embodiments of the present invention belong.

Brief Description of the Drawings

[0023] [Figure 1] The drawing is for explaining the manufacturing process of a conventional double-sided coating electrode. [Figure 2] The drawing is for explaining the position of the electrode drying degree measuring device according to some embodiments and the electrode coating device according to some embodiments. [Figure 3] The top view of the top surface coating electrode in the F area of FIG. 2. [Figure 4] The drawing showing an enlarged view of the F area of FIG. 2.

Modes for Carrying Out the Invention

[0024] The terms and words used herein should not be interpreted in a manner limited to their general or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the meaning of terms and words in order to best describe their own invention.

[0025] In this specification, terms such as “includes” and “have” are intended to specify the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, without prejudice to the presence or possibility of adding one or more other features, numbers, steps, actions, components, parts, or combinations thereof. Furthermore, when a part such as a layer, film, region, or plate is said to be “on top” of another part, this includes not only when it is “directly on top” of the other part, but also when there is another part in between. Conversely, when a part such as a layer, film, region, or plate is said to be “below” another part, this includes not only when it is “directly below” the other part, but also when there is another part in between.

[0026] The embodiments and drawings are illustrative of the present invention and do not represent the entire technical concept of the invention; therefore, there may be a variety of equivalents and modifications that can substitute for them.

[0027] Furthermore, in describing the present invention, if it is determined that a specific description of a known configuration or function may obscure the gist of the invention, such detailed description will be omitted.

[0028] Since the drawings are provided to give a more complete explanation of the invention to an ordinary person of the art, the shapes, sizes, and numbers of the components in the drawings may be exaggerated, omitted, or shown schematically for the sake of clarity. The shapes, sizes, proportions, and numbers of each component in the drawings do not fully reflect the actual shapes, sizes, proportions, and numbers of each component.

[0029] In this specification, “top surface of current collector B” means one surface of current collector B to which the slurry is first coated during the manufacturing process of a double-sided coated electrode. In this specification, “back surface of current collector B” means the surface opposite to one surface of current collector B to which the slurry is first coated during the manufacturing process of a double-sided coated electrode. In this specification, “machine direction (MD) of current collector B” means the direction of movement of the current collector as it is transported by the multiple rollers R1 to R11 during the manufacturing of a double-sided coated electrode.

[0030] One aspect of the present invention relates to an electrode drying degree measuring device.

[0031] Before describing the electrode drying degree measuring device according to some embodiments, the process of manufacturing a double-sided coated electrode will be described with reference to Figure 2. Figure 2 is a diagram illustrating the location of the electrode drying degree measuring device according to some embodiments and the electrode coating device according to some embodiments.

[0032] Multiple rollers R1 to R11 transport the current collector B. The arrows inside each of the multiple rollers R1 to R11 shown in Figure 2 indicate the respective rotation directions of the multiple rollers R1 to R11.

[0033] The top surface coating apparatus C1 coats the top surface of the current collector B with the first slurry S1. In non-limiting examples, the top surface coating apparatus C1 may be a slot die. In non-limiting examples, the first slurry S1 may include an active material, a binder, a conductive material, and a solvent.

[0034] The top surface drying apparatus D1 dries the first slurry S1 coated on the top surface of the current collector B, evaporating the solvent in the first slurry S1. This produces a top surface coated electrode in which the first active material layer A1 is located on the top surface of the current collector B. The first active material layer A1 may include an active material, a binder, a conductive material, etc. As a non-limiting example, the top surface drying apparatus D1 may inject air onto the first slurry S1 to evaporate the solvent in the first slurry S1. As a non-limiting example, there may be multiple regions within the top surface drying apparatus D1 with different air temperatures, air injection speeds, air injection volumes, etc.

[0035] The back surface coating apparatus C2 coats the back surface of the current collector B with the second slurry S2. In non-limiting examples, the back surface coating apparatus C2 may be a slot die. In non-limiting examples, the second slurry S2 may include an active material, a binder, a conductive material, and a solvent. In non-limiting examples, the first slurry S1 may have the same composition, viscosity, etc., as the second slurry S2. In non-limiting examples, the first slurry S1 may have a different composition, viscosity, etc., as the second slurry S2.

[0036] The back surface drying apparatus D2 dries the second slurry S2 coated on the back surface of the current collector B, evaporating the solvent in the second slurry S2. This produces a double-sided coated electrode in which the second active material layer A2 is located on the back surface of the current collector B. The second active material layer A2 may include an active material, a binder, a conductive material, etc. As a non-limiting example, the second active material layer A2 may have the same composition, thickness, etc. as the first active material layer A1. As a non-limiting example, the second active material layer A2 may have a different composition, thickness, etc. as the first active material layer A1. As a non-limiting example, the back surface drying apparatus D2 can inject air onto the second slurry S2 to evaporate the solvent in the second slurry S2. As a non-limiting example, there may be multiple regions within the back surface drying apparatus D2 with different air temperatures, air injection speeds, air injection volumes, etc.

[0037] The number and arrangement of the plurality of rollers R1 to R11 shown in FIG. 2; the arrangement of the top surface coating device C1, the top surface drying device D1, the back surface coating device C2, and the back surface drying device D2; and the thicknesses of the current collector B, the first slurry S1, the first active material layer A1, the second slurry S2, and the second active material layer A2 are merely exemplary.

[0038] As a non-limiting example, the current collector B can include one or more of copper, stainless steel, aluminum, nickel, titanium, fired carbon; and copper, aluminum, or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.

[0039] As a non-limiting example, the active material can be a positive electrode active material. As a non-limiting example, the positive electrode active material can be a lithium-iron-based oxide (e.g., LiFePO4, etc.), a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-y1 Mn y1 O2 (where 0 < y1 < 1) and LiMn 2-z1 Ni z1 O4 (where 0 < z1 < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-y2 Co y2 O2 (where 0 < y2 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-y3 Mn y3 O2 (where 0 < y3 < 1) and LiMn 2-z2 Co z2 O4 (where 0 < z2 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p1 Co q1 Mn r1 )O2 (where 0 < p1 < 1, 0 < q1 < 1, 0 < r1 < 1, p1 + q1 + r1 = 1), Li(Ni p2 Co q2 Mn r2)O4 (where 0 < p2 < 2, 0 < q2 < 2, 0 < r2 < 2, p2 + q2 + r2 = 2), lithium-nickel-cobalt-metal (M) oxide (e.g., Li(Ni p3 Co q3 Mn r3 M s1 )O2 (where M is selected from the group consisting of Al, Cu, Fe, V, Cr, Ti, Zr, Zn, Ta, Nb, Mg, B, W, and Mo, and p3, q3, r3, and s1 are the atomic fractions of independent elements, 0 < p3 < 1, 0 < q3 < 1, 0 < r3 < 1, 0 < s1 < 1, and p3 + q3 + r3 + s1 = 1), etc.) and can include one or more of these mixtures.

[0040] As a non-limiting example, the active material can be a negative electrode active material. As a non-limiting example, the negative electrode active material includes lithium metal; graphite-based carbon materials such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite; amorphous carbon materials such as soft carbon and hard carbon;. Metals such as Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn or alloys of the metals with lithium; PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3 (0 ≤ x ≤ 1), Li x WO2 (0 ≤ x ≤ 1), Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); Si, SiO x(0 < x ≤ 2), Si-Y alloy (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO2, Sn-Y (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), and one or more of mixtures thereof can be included.

[0041] As a non-limiting example, the binder can include one or more of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, styrene-butadiene rubber-carboxymethyl cellulose fluorine rubber, and mixtures thereof.

[0042] As a non-limiting example, the conductive material can include one or more of carbon nanotubes, graphite; carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, nickel powder; conductive whiskers such as zinc oxide, potassium titanate; conductive metal oxides such as titanium oxide; polyphenylene; and mixtures thereof.

[0043] As a non-limiting example, the solvent can include one or more of organic solvents such as N-methylpyrrolidone, dimethylformamide, acetone, dimethylacetamide, and mixtures thereof; and water.

[0044] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0045] Figure 2 is a diagram illustrating the position of an electrode drying degree measuring device and an electrode coating device according to some embodiments.

[0046] In some embodiments, the electrode drying degree measuring device 100 can be positioned behind the top surface drying device D1 with reference to the mechanical direction (MD) of the current collector. In some embodiments, the electrode drying degree measuring device 100 can be positioned in front of the first roller R5 which is located behind the top surface drying device D1 with reference to the mechanical direction (MD) of the current collector.

[0047] In some embodiments, the electrode drying degree measuring device 100 can be positioned in front of the back surface coating device C2 with respect to the mechanical direction (MD) of the current collector. In some embodiments, the electrode drying degree measuring device 100 can be positioned in front of the roller R8 facing the back surface coating device C2 with respect to the mechanical direction (MD) of the current collector. In some embodiments, the electrode drying degree measuring device 100 can be positioned behind the first roller R7 which is located in front of the back surface coating device C2 with respect to the mechanical direction (MD) of the current collector.

[0048] Figure 3 is a top view of the top surface coated electrode in area F of Figure 2. Referring to Figure 3, the first active material layer A1 has a center portion A1C and a side portion A1S. Although Figure 3 shows the number of first active material layers A1 as one, this is illustrative, and there may be multiple first active material layers.

[0049] In some embodiments, the electrode dryness measuring device 100 can be configured to measure the dryness of the center portion A1C and the side portion A1S of the first active material layer A1, respectively. In some embodiments, the electrode dryness measuring device 100 can be configured to measure the dryness of the center portion A1C of the first active material layer A1 from the brightness of the center portion A1C of the first active material layer A1. In some embodiments, the electrode dryness measuring device 100 can be configured to measure the dryness of the side portion A1S of the first active material layer A1 from the brightness of the side portion A1S of the first active material layer A1.

[0050] As described above, the first active material layer A1 is formed by evaporating the solvent from the first slurry S1. If the solvent does not evaporate sufficiently from the first slurry S1, the solvent will remain in the first active material layer A1. When the solvent is present in the first active material layer A1 in this way, the reflectance of the surface of the first active material layer A1 decreases due to the solvent, and the brightness of the first active material layer A1 decreases. The greater the amount of solvent present in the first active material layer A1, the lower the brightness of the first active material layer A1 becomes, so the degree of drying of the first active material layer A1 can be measured from its brightness. That is, the degree of drying of the first active material layer A1 can be quantified through its brightness, so a correlation can be derived between the process variables of the top surface coating apparatus C1 and the top surface drying apparatus D1 that can affect the degree of drying of the first active material layer A1 and the degree of drying of the first active material layer A1.

[0051] As a non-limiting example, the lightness may be the value V in the HSV (Hue, Saturation, Value) color space. As a non-limiting example, the lightness may be the mu (μ) in the RGB (Red, Green, Blue) color space. The mu is the value obtained by adding the R, G, and B channel values ​​and then dividing by 3. As a non-limiting example, the lightness may be the lightness in the Munsell color system.

[0052] Figure 4 is a magnified view of area F in Figure 2.

[0053] In some embodiments, the electrode dryness measuring device 100 may include an image sensor 110 configured to calculate the brightness of the center portion A1C and the side portion A1S of the first active material layer A1 from an image of the first active material layer A1. In some embodiments, the image sensor 110 may include a camera, illumination, and a data processing unit. In some embodiments, the camera may capture an image of the first active material layer A1. In some embodiments, the illumination may irradiate the first active material layer A1 with light. As a non-limiting example, the illumination may be LED illumination. In some embodiments, the data processing unit may be configured to calculate the brightness of the center portion A1C and the side portion A1S of the first active material layer A1 from an image of the first active material layer A1 captured by the camera. In some embodiments, the brightness of the center portion A1C of the first active material layer A1 may be the average of the brightness measured at multiple measurement points selected in the portion of the image of the first active material layer A1 corresponding to the center portion A1C of the first active material layer A1. In some embodiments, the multiple measurement points may be uniformly distributed in the portion of the image of the first active material layer A1 corresponding to the center portion A1C of the first active material layer A1. In some embodiments, the brightness of the side portion A1S of the first active material layer A1 may be the average of the brightness measured at multiple measurement points selected in the portion of the image of the first active material layer A1 corresponding to the side portion A1S of the first active material layer A1. In some embodiments, the multiple measurement points may be uniformly distributed in the portion of the image of the first active material layer A1 corresponding to the side portion A1S of the first active material layer A1.

[0054] In some embodiments, the image sensor 110 may include multiple cameras, multiple illuminators, or multiple data processing units. As a non-limiting example, the image sensor 110 may include three cameras. In this case, one camera may capture the center portion A1C of the first active material layer A1, and the remaining two cameras may capture the side portions A1S of the first active material layer A1. As a non-limiting example, the image sensor 110 may include three illuminators. In this case, one illuminator may illuminate the center portion A1C of the first active material layer A1, and the remaining two illuminators may illuminate the side portions A1S of the first active material layer A1. As a non-limiting example, the image sensor 110 may include three data processing units. In this case, one data processing unit may be configured to calculate the brightness of the center portion A1C of the first active material layer A1, and the remaining two data processing units may be configured to calculate the brightness of the side portions A1S of the first active material layer A1.

[0055] In some embodiments, the electrode dryness measuring device 100 may include an optical sensor 110' configured to irradiate the first active material layer A1 with light, analyze the light reflected from the first active material layer A1, and calculate the brightness of the center portion A1C and the side portion A1S of the first active material layer A1, respectively. In some embodiments, the brightness of the center portion A1C of the first active material layer A1 may be the average of the brightness measured at a plurality of measurement points selected in the center portion A1C of the first active material layer A1. In some embodiments, the plurality of measurement points may be uniformly distributed in the center portion A1C of the first active material layer A1. In some embodiments, the brightness of the side portion A1S of the first active material layer A1 may be the average of the brightness measured at a plurality of measurement points selected in the side portion A1S of the first active material layer A1. In some embodiments, the plurality of measurement points may be uniformly distributed in the side portion A1S of the first active material layer A1.

[0056] In some embodiments, the optical sensor 110' may include multiple spectrophotometers. As a non-limiting example, the optical sensor 110' may include three spectrophotometers. In this case, one spectrophotometer can calculate the brightness of the center portion A1C of the first active material layer A1, and the remaining two spectrophotometers can calculate the brightness of the side portions A1S of the first active material layer A1.

[0057] Generally, the sides of the active material layer dry faster than the center, and excessive drying of the sides can expose the current collector. When the current collector is exposed in this way, cracks can form in the electrodes. Some embodiments are designed to take this drying behavior of the active material layer into consideration.

[0058] If the brightness of the center portion A1C of the first active material layer A1 is lower than the reference value, it means that the first active material layer A1 is not sufficiently dried. If the brightness of the side portion A1S of the first active material layer A1 is higher than the reference value, it means that the side portion A1S of the first active material layer A1 has been excessively dried. This is because when the current collector B is exposed on the side portion A1S of the first active material layer A1, the reflectance of the side portion A1S of the first active material layer A1 increases due to the current collector B, and the brightness of the side portion A1S of the first active material layer A1 increases.

[0059] The aforementioned reference value may be determined from the average brightness of the active material layer in which the degree of dryness is deemed appropriate. In some embodiments, the reference value may be determined to be the same as the average brightness of the active material layer in which the degree of dryness is deemed appropriate. In some embodiments, the reference value may be determined to be approximately 98% to approximately 102% of the average brightness value of the active material layer in which the degree of dryness is deemed appropriate, taking into account process errors.

[0060] In some embodiments, the electrode dryness measuring device 100 may include a transmitting unit 120 configured to transmit a defect signal to a display device 200 or a control device 30 if the brightness of the center portion A1C of the first active material layer A1 is lower than a first reference value, or if the brightness of the side portion A1S of the first active material layer A1 is higher than a second reference value. In some embodiments, the first reference value may be set to approximately 98% of the average brightness value of the active material layer in which the dryness is deemed appropriate, taking into account process errors. In some embodiments, the second reference value may be set to approximately 102% of the average brightness value of the active material layer in which the dryness is deemed appropriate, taking into account process errors.

[0061] When the transmitting unit 120 transmits a fault signal to the display device 200, the display device 200 may display an alarm such as sound and light so that the operator can recognize that the drying of the first active material layer A1 is inadequate.

[0062] When the transmitting unit 120 transmits a fault signal to the control device 300, the control device 300 can stop the operation of the rollers R1 to R11, the top surface coating device C1, the top surface drying device D1, the back surface coating device C2, and the back surface drying device D2.

[0063] Another aspect of the present invention relates to an electrode coating apparatus.

[0064] Figure 2 is a diagram illustrating the position of an electrode drying degree measuring device and an electrode coating device according to some embodiments.

[0065] In some embodiments, the electrode coating apparatus 10 may include the top surface drying apparatus D1, the back surface coating apparatus C2, and the electrode drying degree measuring apparatus 100 located between the top surface drying apparatus D1 and the back surface coating apparatus C2, with reference to the machine direction (MD) of the current collector B.

[0066] In some embodiments, the electrode coating apparatus 10 may further include a top surface coating apparatus C1 and a back surface drying apparatus D2.

[0067] In some embodiments, the electrode coating apparatus 10 may further include a plurality of rollers R1 to R11.

[0068] In some embodiments, the top surface coating device C1, the top surface drying device D1, the electrode drying degree measuring device 100, the back surface coating device C2, and the back surface drying device D2 can be arranged sequentially with reference to the machine direction (MD) of the current collector B.

[0069] The descriptions of the top surface coating device C1, the top surface drying device D1, the electrode drying degree measuring device 100, the back surface coating device C2, and the back surface drying device D2 are the same as those described above, so redundant explanations will be omitted.

[0070] The above description is for illustrative purposes only. The scope of the present invention should be interpreted by the claims, and all technical ideas within the same or equivalent scope should be interpreted as being included within the scope of the present invention. [Explanation of Symbols]

[0071] 10: Electrode coating device A1: First active material layer A2: Second active material layer B: Current collector C1: Top surface coating device C2: Back surface coating device D1: Top surface drying device D2: Back surface drying device R1~R11: Multiple rollers S1: Slurry No. 1 S2: Second Slurry 100: Electrode dryness measuring device 110: Image sensor 110': Optical sensor 120: Transmitter 200:Display device 300: Control device A1C: Center section A1S: Side section

Claims

1. Located behind the machine direction (MD) of the current collector, relative to the machine direction of the current collector, the top surface drying device is configured to dry the slurry coated on the top surface of the current collector. An electrode drying degree measuring device configured to measure the degree of drying of the center and side portions of the active material layer dried by the top surface drying device.

2. The electrode drying degree measuring device is The degree of dryness of the center portion of the active material layer is measured from the brightness of the center portion of the active material layer. The electrode drying degree measuring device according to claim 1, configured to measure the degree of drying of the side portion of the active material layer from the brightness of the side portion of the active material layer.

3. The electrode drying degree measuring device according to claim 2, wherein the electrode drying degree measuring device includes an image sensor configured to calculate the brightness of the center portion and the side portion of the active material layer from an image of the active material layer.

4. The electrode drying degree measuring device according to claim 2, wherein the electrode drying degree measuring device includes an optical sensor configured to irradiate the active material layer with light and analyze the light reflected from the active material layer to calculate the brightness of the center portion and the side portion of the active material layer, respectively.

5. The electrode drying degree measuring device according to claim 2, further comprising a transmitting unit configured to transmit a fault signal to a display device when the brightness of the center portion of the active material layer is lower than a reference value, or the brightness of the side portion of the active material layer is higher than the reference value.

6. The electrode drying degree measuring device according to claim 2, further comprising a transmitting unit configured to transmit a fault signal to a control device when the brightness of the center portion of the active material layer is lower than an undried standard value, or when the brightness of the side portion of the active material layer is higher than an over-dried standard value.

7. A top surface drying device configured to dry a first slurry coated on the top surface of a current collector, A back surface coating apparatus configured to coat the back surface of the current collector with a second slurry, An electrode drying degree measuring device according to any one of claims 1 to 6, located between the top surface drying device and the back surface coating device, An electrode coating apparatus, including one.

8. The electrode coating apparatus is A top surface coating device configured to coat the top surface of the current collector with a first slurry, A back surface drying device configured to dry the second slurry coated on the back surface of the current collector, The electrode coating apparatus according to claim 7, further comprising:

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