FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10, rule 13) “DRY QUALITY EVALUATION DEVICE FOR ELECTRODE AND DRY QUALITY EVALUATION METHOD FOR ELECTRODE” LG ENERGY SOLUTION, LTD., of Tower 1, 108, Yeoui-daero, Yeongdeungpo-gu, Seoul 07335, Republic of Korea The following specification particularly describes the invention and the manner in which it is to be performed. 2 【Description】 【Title of the Invention】 DRY QUALITY EVALUATION DEVICE FOR ELECTRODE AND DRY QUALITY EVALUATION METHOD FOR ELECTRODE 5 【Technical Field】 [1] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0109043, filed on August 28, 2020, and the entire contents of the Korean patent application are incorporated herein by reference. [2] The present invention relates to an apparatus for evaluating drying quality of an 10 electrode and a method for evaluating drying quality of an electrode, and more particularly, to an apparatus for evaluating drying quality of an electrode and a method for evaluating drying quality of an electrode by measuring a simple color coordinate value of an electrode. 【Background Art】 [3] Recently, secondary batteries capable of charging and discharging have been 15 widely used as energy sources of wireless mobile devices. In addition, the secondary battery has attracted attention as an energy source of an electric vehicle, a hybrid electric vehicle, etc., which are proposed as a solution for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuel. Therefore, the types of applications using the secondary battery are currently much diversified due to the advantages of the secondary battery, and it is expected that the secondary 20 battery will be applied to many fields and products in the future. 3 [4] Such secondary batteries may be classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc., depending on the composition of the electrode and the electrolyte, and among them, the amount of use of lithium-ion polymer batteries that are less likely to leak electrolyte and are easy to manufacture is on the increase. In general, 5 secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is embedded in a cylindrical or rectangular metal can, depending on the shape of a battery case, and pouch-type batteries in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. The electrode assembly built into the battery case is composed of a positive electrode, a negative electrode, and a separator interposed 10 between the positive electrode and the negative electrode, and is a power generating element capable of charging and discharging. The electrode assembly is classified into a jelly-roll type wound with a separator interposed between the positive electrode and the negative electrode which are long sheet-shaped and are coated with active materials, and a stack type in which a plurality of positive electrodes and negative electrodes of a predetermined size are sequentially 15 stacked while a separator is interposed therebetween. [5] Such an electrode may be manufactured by applying an electrode slurry containing an electrode active material and a solvent on a current collector to form an electrode active material layer, followed by drying and rolling. At this time, the quality of the electrode is determined according to the drying conditions. If the amount of drying heat is excessive, a 20 significant amount of the binder in the electrode slurry moves to the surface during the drying process, thereby reducing the adhesive force of the electrode. If the amount of drying heat is low, the solvent remains in the electrode, causing roll contamination in the coating and rolling process. 4 This increase in roll contamination causes defects on the electrode surface, and the residual solvent in the electrode becomes a major factor in safety problems such as gas generation and swelling in the battery, so it is necessary to develop an evaluation method to determine whether the electrode is dry. 5 [6] In this regard, conventionally, a device such as a web-gauge was used to measure the change in weight of the electrode to evaluate the degree of drying. Specifically, the difference in weight of the electrode before and after coating is calculated to calculate the weight per unit area of the electrode slurry before drying, and after drying, the weight per unit area of the electrode slurry is calculated in the same manner. Next, the presence or absence of residual 10 solvent is determined from the difference between the theoretical electrode weight derived from the solid content in the electrode slurry and the weight per unit area of the electrode slurry before drying, and the previously calculated weight per unit area of electrode slurry after drying. [7] However, in this method, the weight of the electrode should be measured three times before coating, after coating and after drying. In addition, in the case of an electrode coated 15 with an electrode slurry on both sides of a current collector, since the weight of the electrode slurry coated on both sides should be measured before and after drying, a total of five weights should be measured, which takes a long time and cost to evaluate. In addition, since the web gauge for measuring the weight of the electrode uses a radioactive isotope such as 85Kr, a radiation exposure problem may occur accordingly. 20 [8] Accordingly, there is a need to develop an apparatus and method for evaluating the drying quality of an electrode that can solve the above problems. 【Disclosure】 5 【Technical Problem】 [9] The present invention is devised to solve the above problems, and an object of the present invention is to provide an apparatus for evaluating drying quality of an electrode and a method for evaluating drying quality of an electrode capable of reducing the time and cost of 5 evaluation and securing safety in the evaluation process by quickly determining the drying level of the electrode by determining the presence or absence of solvent in the electrode in the process. 【Technical Solution】 [10] An apparatus for evaluating drying quality of an electrode according to the present invention includes: an oven configured to provide a space in which an electrode is dried; 10 a measuring unit configured to be positioned at an outlet of the oven and measure a color coordinate value of an electrode active material layer with respect to the dried electrode; and an determination unit configured to determine whether a dry state of the electrode is defective from the color coordinate value, wherein the determination unit sets a reference value, and determines that a dry state of the electrode is defective if the measured color coordinate value is less than the 15 reference value, and a difference between the measured color coordinate value and the reference value is more than a preset value. [11] In one example, the color coordinate value is L*. [12] In another example, the color coordinate value is a gray value according to a gray scale. 20 [13] In one example, the measuring unit includes a spectrophotometer or a colorimeter. 6 [14] In another example, the measuring unit includes an image sensor capable of taking an image of a surface of the electrode active material layer. [15] In one example, the determination unit derives a reference value from an average value of color coordinate values for a plurality of electrodes. 5 [16] In another example, the determination unit derives a reference value from a profile of an electrode color coordinate value according to a residual solvent content in the electrode. [17] In a specific example, the determination unit determines that a dry state of the electrode is defective when a difference between the measured color coordinate value and the 10 reference value is 0.5 or more. [18] Further, the present invention provides a method for evaluating drying quality of an electrode. The method includes: a step of manufacturing an electrode by forming an electrode active material layer including an electrode active material on a current collector, and putting the electrode in an oven of the above described apparatus to thereby dry the electrode; a step of 15 measuring a color coordinate value of the electrode active material layer with respect to the dried electrode; and a step of determining whether the electrode is dry from the color coordinate value, wherein it is determined that a dry state of the electrode is defective when the measured color coordinate value is less than the reference value, and a difference between the measured color coordinate value and the reference value is a predetermined value or more. 20 [19] In a specific example, the electrode may not be rolled. [20] In one example, the color coordinate value is L*. [21] In another example, the color coordinate value is a gray value according to a 7 gray scale. [22] In one example, the step of measuring the color coordinate value of the electrode active material layer may be performed through a spectrophotometer or a colorimeter. [23] In another example, the step of measuring the color coordinate value of the 5 electrode active material layer includes obtaining an image by photographing the surface of the electrode through illumination and an image sensor, and converting the color information of the image into color coordinates. [24] In one example, the reference value may be derived from an average value of color coordinate values for the plurality of electrodes after manufacturing a plurality of 10 electrodes. [25] In another example, the reference value may be derived from a profile of an electrode color coordinate value according to a residual solvent content in the electrode. [26] In this case, the reference value may be derived from a color coordinate value of an electrode that satisfies the content of the residual solvent in the target electrode. 15 [27] Further, it may be determined that the dry state of the electrode is defective when the difference between the measured color coordinate value and the reference value is 0.5 or more. [28] At this time, a residual solvent content in the electrode of the electrode determined as a good product is 1% by weight or less. 20 [29] Further, the present invention provides a method for manufacturing an electrode. The method includes: a step of evaluating drying quality of an electrode according to the above described method of evaluating the drying quality of the electrode; and a step of rolling the 8 electrode determined to be good. 【Advantageous Effects】 [30] According to the present invention, by measuring a simple color coordinate value after manufacturing and drying an electrode, it is possible to simply determine the degree 5 of drying of the electrode and whether or not the drying is defective, thereby reducing the time and cost required for the measurement. In addition, since lighting and sensors are used instead of web gauges as measuring equipment, safety in the evaluation process can be secured. 【Brief Description of the Drawings】 [31] FIG. 1 is a block diagram showing the configuration of an apparatus for 10 evaluating drying quality of an electrode according to the present invention. [32] FIG. 2 is a schematic diagram showing an operating method of an apparatus for evaluating drying quality of an electrode according to the present invention. [33] FIG. 3 is a flowchart showing the procedure of a method for evaluating dry quality of an electrode according to the present invention. 15 [34] FIGS. 4 to 6 are color coordinates of an electrode according to an embodiment of the present invention and a measurement value of the residual moisture amount of the electrode accordingly. 【Detailed Description of the Preferred Embodiments】 [35] Hereinafter, the present invention will be described in detail with reference to 20 the drawings. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may properly define the 9 concept of the terms in order to best describe its invention. The terms and words should be construed as meaning and concept consistent with the technical idea of the present invention. [36] In this application, it should be understood that terms such as "include" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, 5 or a combination thereof described on the specification, and they do not exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts or combinations thereof. Also, when a portion such as a layer, a film, an area, a plate, etc. is referred to as being "on" another portion, this includes not only the case where the portion is "directly on" the another portion but also the case where further another 10 portion is interposed therebetween. On the other hand, when a portion such as a layer, a film, an area, a plate, etc. is referred to as being "under" another portion, this includes not only the case where the portion is "directly under" the another portion but also the case where further another portion is interposed therebetween. In addition, to be disposed "on" in the present application may include the case disposed at the bottom as well as the top. 15 [37] [38] Hereinafter, the present invention will be described in detail with reference to the drawings. [39] FIG. 1 is a block diagram showing the configuration of an apparatus for evaluating drying quality of an electrode according to the present invention. 20 [40] Referring to FIG. 1, an apparatus 10 for evaluating drying quality of an electrode according to the present invention includes: an oven 11 configured to provide a space in which an electrode is dried; a measuring unit 12 configured to be positioned at an outlet of the 10 oven 11 and measure a color coordinate value of an electrode active material layer with respect to the dried electrode; and an determination unit 13 configured to determine whether the electrode is dry from the color coordinate value, wherein the determination unit 13 sets a reference value, and determines that a dry state of the electrode is defective if the measured color 5 coordinate value is less than the reference value, and a difference between the measured color coordinate value and the reference value is more than a preset value. [41] As described above, conventionally, a device such as a web-gauge was used to measure the change in weight of the electrode to evaluate the degree of drying, but in this case, since it is necessary to individually measure the electrode slurry coated on the current collector, 10 it takes a long time and cost for evaluation. In addition, the web gauge for measuring the weight of the electrode has a problem that a worker may be exposed to radiation. [42] However, according to the present invention, by measuring a simple color coordinate value after manufacturing and drying an electrode, it is possible to simply determine the degree of drying of the electrode and whether or not the drying is defective, thereby reducing 15 the time and cost required for the measurement. In addition, since lighting and sensors are used instead of web gauges as measuring equipment, safety in the evaluation process can be secured. [43] [44] Hereinafter, each configuration of the apparatus for evaluating the drying quality of an electrode according to the present invention will be described in detail. 20 [45] FIG. 2 is a schematic diagram showing an operating method of an apparatus for evaluating drying quality of an electrode according to the present invention. [46] Referring to FIG. 2 together with FIG. 1, an oven 11 provides a space in which 11 the electrode 20 is put and dried. The oven 11 includes a hot air nozzle (not shown) or an infrared heater (not shown) for drying the electrode 20 therein. The hot air nozzle and the infrared heater may be arranged to be spaced apart at predetermined intervals along the transport direction of the electrode 20, and apply hot air or infrared rays in a direction perpendicular to the 5 electrode 20. Details of the hot air nozzle and infrared heater are known to those of ordinary skill in the art, and thus detailed descriptions thereof will be omitted. [47] Meanwhile, the electrode 20 is manufactured by forming an electrode active material layer 22 on the current collector 21. [48] In this case, the electrode active material layer 22 may be formed by applying an 10 electrode slurry including an electrode active material, a conductive material, and a binder on the current collector 21. The electrode 20 may be a negative electrode or a positive electrode, and the current collector may be a positive electrode current collector or a negative electrode current collector. [49] In the present invention, the positive electrode collector generally has a 15 thickness of 3 to 500 micrometers. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon or aluminum or stainless steel of which the surface has been treated with carbon, nickel, titanium, silver, or the like. The current collector may have fine irregularities 20 on the surface thereof to increase the adhesion of the positive electrode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible. 12 [50] The sheet for the negative electrode collector generally has a thickness of 3 to 500 micrometers. The negative electrode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples thereof include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or 5 stainless steel of which the surface has been treated with carbon, nickel, titanium, silver or the like, aluminum-cadmium alloy, or the like. In addition, like the positive electrode current collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric. 10 [51] In the present invention, the positive electrode active material is a material capable of causing an electrochemical reaction and a lithium transition metal oxide, and contains two or more transition metals. Examples thereof include: layered compounds such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2) substituted with one or more transition metals; lithium manganese oxide substituted with one or more transition metals; lithium nickel 15 oxide represented by the formula LiNi1-yMyO2 (wherein M = Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn or Ga and contains at least one of the above elements, 0.01 ≦ y ≦ 0.7); lithium nickel cobalt manganese composite oxide represented by the formula Li1+zNibMncCo1-(b+c+d)MdO(2-e)Ae such as Li1+zNi1/3Co1/3Mn1/3O2, Li1+zNi0.4Mn0.4Co0.2O2 etc. (wherein -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, b+c+d<1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl); olivine-based 20 lithium metal phosphate represented by the formula Li1+xM1-yM'yPO4-zXz (wherein M = transition metal, preferably Fe, Mn, Co or Ni, M'= Al, Mg or Ti, X = F, S or N, and -0.5≤x≤0.5, 0≤y≤0.5, 0≤z≤0.1). 13 [52] Examples of the negative electrode active material include carbon such as nongraphitized carbon and graphite carbon; metal complex oxide such as LixFe2O3(0≤x≤1), LixWO2(0≤x≤1), SnxMe1-xMe’yOz (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, groups 1, 2, and 3 of the periodic table, halogen; 0 [85] Referring to FIG. 3 together with FIGS. 1 and 2, first, an electrode 20 is 15 manufactured by forming an electrode active material layer 22 including an electrode active material on the current collector 21 in order to measure color coordinate values. Details of the electrode are the same as described above. [86] When manufacturing of the electrode 20 is completed, the electrode 20 is put into the oven 11 and dried. In this case, the drying time and the drying heat amount may be 20 determined by the specifications of the electrode, for example, the loading amount of the electrode active material or the solvent content in the electrode slurry. The dried electrode 20 is discharged out of the oven 11. 21 [87] [88] [89] When drying of the electrode 20 is completed, a color coordinate value is measured for the dried electrode 20. At this time, the color coordinate value of the electrode 5 active material layer 22 is measured by the measuring unit 12 according to the apparatus 10 for evaluating dry quality of the electrode as described above. Since the measuring unit 12 is located near the outlet of the oven 11, the color coordinate value can be measured directly with respect to the electrode 20 discharged from the oven 11. As described above, the color coordinate value of the electrode 20 may be a color coordinate value measured at a certain point of a certain 10 electrode active material layer 22, or may be the average value of the color coordinate values measured at the measurement points after selecting several measurement points in the electrode active material layer 22. [90] The present invention installs only a simple device capable of measuring color coordinates near the outlet of the oven and quantifies the dry state of the electrode through color 15 coordinate measurement, thereby simplifying the measuring method and reducing the time and cost required for evaluation. [91] Meanwhile, in a specific example of the present invention, the electrode may not be rolled. That is, the present invention does not evaluate the electrode that has passed through the rolling process, but by performing the evaluation on the electrode that has not 20 undergone the rolling process, it is possible to filter out defective electrodes before the rolling process and significantly reduce the defect rate after the rolling process. This can prevent contamination of the rolling roll, etc. due to residual solvent in the electrode in the rolling 22 process. However, the present invention is not limited thereto, and color coordinates may be measured at any stage after drying the electrode. [92] In one example, the color coordinate value may be L*. As described above, L* is a value related to the measured lightness of the object and may be displayed from 0 to 100. 5 When the electrode is undried, the average refractive index on the surface of the electrode active material layer decreases due to the solvent remaining in the electrode active material layer, so that it exhibits a darker color than the dried electrode, and the L* value will be measured smaller than that of a normal case. [93] In another example, the color coordinate value may be a gray value according to 10 a gray scale. That is, an image of the dry surface of the electrode may be converted into a gray scale capable of confirming only the contrast, and a gray value may be measured therefrom to determine whether the electrode is dried. When the electrode is undried, it exhibits a darker color than the dried electrode, and the gray value will be measured smaller than that of a normal case. [94] As described above, in the present invention, the color coordinates that can 15 uniformly measure the contrast of the electrode surface are used, and whether the electrode is dry or not can be determined by quantitatively measuring the contrast of the surface of the electrode active material layer. [95] In one example, a colorimeter may be used as a sensor that measures a color coordinate value of the electrode active material layer. Specifically, the step of measuring the 20 color coordinate value of the electrode active material layer may be performed through a spectrophotometer or a colorimeter. In this case, a color coordinate value may be directly measured on the surface of the electrode active material layer. 23 [96] For example, the color coordinate value may be measured using a CM2600d manufactured by Konica Minolta as the colorimeter. Specifically, in order to measure the color coordinate value, the measurement mode was set to SCI (Specular Component Included) or SCE (Specular Component Excluded), standard light source D65 (color temperature: 6500K), CIE 5 1964 10° standard observer using Konica Minolta's CM2600d as the colorimeter, followed by white calibration, followed by touching the colorimeter to the location desired to be measured. [97] In another example, the step of measuring the color coordinate value of the electrode active material layer includes obtaining an image by photographing the surface of the electrode through illumination and an image sensor, and converting the color information of the 10 image into color coordinates. In this case, an image of the electrode surface is obtained by photographing the electrode, specifically, the surface of the electrode active material layer through the image sensor. In this case, a camera may be used as the image sensor. When an image is obtained, it is converted into a color coordinate system to be measured, and a color coordinate value is measured. For example, after converting an image photographed through a 15 camera into a gray scale, the gray value or L* value of the corresponding image may be measured. [98] In the present invention, since the LED light source is used as the lighting, the safety of the operator can be secured compared to the web gauge. [99] 20 [100] [101] When the color coordinate value is measured, it is determined from this whether a dry state of the electrode is defective. The present invention includes a step of determining it as 24 a good product if the measured color coordinate value satisfies a preset electrode drying quality evaluation criterion and determining it as a defective product if it does not satisfy a preset electrode drying quality evaluation criterion. This is performed by the determination unit 13 included in the apparatus for evaluating the drying quality of the electrode as described above. 5 [102] Specifically, in the present invention, a reference value of a color coordinate value for determining whether a dry state of the electrode is defective is set, and it is determined that a dry state of the electrode is defective when the measured color coordinate value is less than the reference value, and a difference between the measured color coordinate value and the reference value is a predetermined value or more. 10 [103] In one example, the reference value may be derived from an average value of color coordinate values for the plurality of electrodes after manufacturing a plurality of electrodes. In this case, after manufacturing a plurality of electrodes in advance to derive a reference value, color coordinate values for them may be measured. Alternatively, an average value of color coordinate values measured for a plurality of electrodes to be measured may be 15 obtained. At this time, if the color coordinate value of any one of the plurality of electrodes is smaller than the average value by a predetermined value or more, the corresponding electrode may be determined as a defect. [104] In another example, the reference value may be derived from a profile of an electrode color coordinate value according to a residual solvent content in the electrode. The 20 reference value may be derived from a color coordinate value of an electrode that satisfies the content of the residual solvent in the target electrode. [105] Specifically, a plurality of electrode samples are prepared under the same 25 conditions and the same process as the electrode to be measured, and after drying, the color coordinate value and the solvent content in the electrode are measured. Subsequently, a color coordinate value according to the solvent content in the electrode of the electrode sample may be converted into a database. For example, in order to determine the trend of color coordinate 5 values according to the solvent content in the electrode, it may be shown as a graph and converted into a database. Subsequently, in the database, a color coordinate value of an electrode that satisfies a target solvent content in the electrode may be set as a reference value. [106] Further, in the present invention, it is determined that a dry state of the electrode is defective when the measured color coordinate value is less than the reference value, and a 10 difference between the measured color coordinate value and the reference value is a predetermined value or more. The predetermined value can also be derived from the profile, for example. [107] In a specific example, it may be determined that the dry state of the electrode is defective when the difference between the measured color coordinate value and the reference 15 value is 0.5 or more. That is, when the measured color coordinate value is smaller than the reference value by 0.5 or more, it may be determined that the dry state of the corresponding electrode is defective. When the difference between the reference value and the measured color coordinate value is within the above range, an electrode that satisfies the residual solvent content in the target electrode may be determined as a good product. 20 [108] In this case, the residual solvent content in the electrode of the electrode determined as good product may be 1% by weight or less, and in detail, 0.5% by weight or less. When the residual solvent content in the electrode is within the above range, the drying quality 26 of the electrode is excellent, so that roll contamination in the rolling process, gas generation, swelling phenomenon, etc. in the battery can be prevented. The content of the residual solvent in the electrode of the electrode determined as a good product may be changed depending on the composition of the electrode and the solid content in the electrode. In this way, the present 5 invention can detect up to 1.0% by weight or less of moisture through measurement of color coordinates. [109] [110] Further, the present invention provides a method for manufacturing an electrode. The method includes: a step of evaluating drying quality of an electrode according to a method 10 of evaluating the drying quality of the above described electrode; and a step of rolling the electrode determined to be good. [111] The electrode manufactured according to the method of manufacturing an electrode according to the present invention can be used to manufacture a lithium secondary battery as a positive electrode or a negative electrode, and since the drying quality is excellent, 15 the defect rate of the lithium secondary battery can be reduced. [112] The lithium secondary battery may be usefully used in portable devices such as mobile phones, notebook computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs). [113] 20 [114] Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being 27 limited to the examples described below. The examples of the present invention are provided to more fully describe the present invention to those skilled in the art. [115] [116] Example 1 5 [117] [118] An electrode slurry was prepared by mixing 41 parts by weight of natural graphite, 0.5 parts by weight of a conductive material, 2.5 parts by weight of SBR, and 1 part by weight of CMC with 55 parts by weight of water. [119] The electrode slurry was coated on one surface of a copper current collector having a thickness of 8 μm at a loading amount of 0.014 g/cm2 10 and dried to form an electrode active material layer having a thickness of 144 μm to prepare an electrode. Subsequently, an active material layer was formed on the other surface of the current collector under the same process conditions, and an electrode having a total active material layer thickness of 288 μm formed on both surfaces of the copper current collector was manufactured. At this time, the solid 15 content in the electrode slurry was 45% by weight. [120] [121] After manufacturing a plurality of the electrodes, the measurement mode was set to SCI, standard light source D65 (color temperature: 6500K), CIE 1964 10° standard observer using Konica Minolta's CM2600d as a colorimeter, followed by white correction, 20 followed by touching the colorimeter to the location desired to be measured, to thereby measuring the color coordinate value (L*) of the prepared electrode active material layer. [122] 28 [123] For the prepared plurality of electrodes, an average value of color coordinate values was calculated, and this was used as a reference value. In this case, the reference value was 35.50 as shown in FIG. 4. [124] 5 [125] [126] For the plurality of electrodes manufactured above, if the color coordinate value is smaller than the reference value, and the difference between the reference value and the measured color coordinate value is 0.5 or more, it was determined as defective. A point at which the difference between the reference value and the color coordinate value is 0.5 is shown by a 10 dotted line in FIG. 4. [127] [128] Example 2 [129] When manufacturing the electrode, it was determined whether a dry state of the electrode is defective in the same manner as in Example 1, except that the content of SBR as a 15 binder was 1.0 part by weight. In this case, the reference value was 35.28 as shown in FIG. 5. In addition, a point at which the difference between the reference value and the color coordinate value is 0.5 is shown by a dotted line in FIG. 5. [130] [131] Example 3 20 [132] It was determined whether a dry state of the electrode was defective in the same manner as in Example 1 except that when manufacturing the electrode, a mixture of natural graphite and artificial graphite in a ratio of 1:1 was used, and a solid content of 40% by weight 29 was used. In this case, the reference value was 38.66 as shown in FIG. 6. In addition, a point at which the difference between the reference value and the color coordinate value is 0.5 is shown by a dotted line in FIG. 6. [133] 5 [134] Experimental Example [135] For the electrodes measured in Examples 1 to 3, the residual solvent content of the electrode was measured. [136] The residual solvent content of the electrode can be measured by the following method. 10 [137] Specifically, the weight per unit area of the copper current collector before coating is measured. Subsequently, after coating the electrode slurry, the weight per unit area of the electrode (weight of the electrode active material layer + weight of the copper current collector) was measured, and then the weight per unit area of the electrode active material layer before drying is calculated by excluding the weight per unit area of the copper current collector. 15 [138] Thereafter, the electrode is dried, and the weight per unit area of the electrode is measured after drying, and the weight per unit area of the electrode active material layer after drying is measured by excluding the weight per unit area of the copper current collector. [139] The content of the residual solvent may be derived from the weight of the electrode active material layer before and after drying and the solid content included in the 20 electrode slurry. [140] In this case, the weight per unit area can be measured using a web gauge. Any web gauge available on the market can be used. For example, Thermo Fisher's Thermo 30 Scientific™ web gauge may be used. [141] For the residual solvent content of the electrode measured as described above, color coordinate values (L*) according to the residual solvent content are shown in FIGS. 4 to 6, respectively. 5 [142] Referring to FIGS. 4 to 6, as the content of residual solvent in the electrode increases, the color coordinate value tends to decrease. In addition, the electrode determined to be good (corresponding to the electrode with a difference between the measured color coordinate value and the reference value of less than 0.5, the electrode located above the dotted line) has a residual solvent content of 0.5% by weight or less (Examples 1 and 2) or 1.0% by weight or less 10 (Example 3), which has satisfied the standard of good quality. That is, in the present invention, it is possible to detect a moisture content of 1.0% by weight or less through measurement of color coordinates. [143] [144] The above description is merely illustrative of the technical idea of the present 15 invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the drawings disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these drawings. The scope of 20 protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention. 31 [145] [146] On the other hand, in this specification, terms indicating directions such as up, down, left, right, before, and after are used, but it is obvious that these terms are for convenience of description only and may change depending on the location of the object or the location of the 5 observer. [147] [148] [Description of reference numerals] [149] 10: apparatus for evaluating drying quality of electrode [150] 11: oven 10 [151] 12: measuring unit [152] 13: determination unit [153] 20: electrode [154] 21: current collector [155] 22: electrode active material layer We Claim: 【Claim 1】 An apparatus for evaluating drying quality of an electrode, the apparatus comprising: an oven configured to provide a space in which an electrode is dried; 5 a measuring unit configured to be positioned at an outlet of the oven and measure a color coordinate value of an electrode active material layer with respect to the dried electrode; and an determination unit configured to determine whether a dry state of the electrode is defective from the color coordinate value, wherein the determination unit sets a reference value, and determines that a dry state of 10 the electrode is defective if the measured color coordinate value is less than the reference value, and a difference between the measured color coordinate value and the reference value is more than a preset value. 【Claim 2】 15 The apparatus of claim 1, wherein the color coordinate value is L*. 【Claim 3】 The apparatus of claim 1, wherein the color coordinate value is a gray value according to a gray scale. 20 33 【Claim 4】 The apparatus of claim 1, wherein the measuring unit includes a spectrophotometer or a colorimeter. 5 【Claim 5】 The apparatus of claim 1, wherein the measuring unit includes an image sensor capable of taking an image of a surface of the electrode active material layer. 【Claim 6】 10 The apparatus of claim 1, wherein the determination unit derives a reference value from an average value of color coordinate values for a plurality of electrodes. 【Claim 7】 The apparatus of claim 1, wherein the determination unit derives a reference value from 15 a profile of an electrode color coordinate value according to a residual solvent content in the electrode. 【Claim 8】 The apparatus of claim 2, wherein the determination unit determines that a dry state of 20 the electrode is defective when a difference between the measured color coordinate value and the 34 reference value is 0.5 or more. 【Claim 9】 A method for evaluating drying quality of an electrode, the method comprising: 5 a step of manufacturing an electrode by forming an electrode active material layer including an electrode active material on a current collector, and putting the electrode in an oven of the apparatus according to claim 1 to thereby dry the electrode; a step of measuring a color coordinate value of the electrode active material layer with respect to the dried electrode; and 10 a step of determining whether a dry state of the electrode is defective from the color coordinate value, wherein it is determined that a dry state of the electrode is defective when the measured color coordinate value is less than the reference value, and a difference between the measured color coordinate value and the reference value is a predetermined value or more. 15 【Claim 10】 The method of claim 9, wherein the electrode is not rolled. 【Claim 11】 20 The method of claim 9, wherein the color coordinate value is L*. 35 【Claim 12】 The method of claim 9, wherein the color coordinate value is a gray value according to a gray scale. 5 【Claim 13】 The method of claim 9, wherein the step of measuring the color coordinate value of the electrode active material layer is performed through a spectrophotometer or a colorimeter. 【Claim 14】 10 The method of claim 9, wherein the step of measuring the color coordinate value of the electrode active material layer includes obtaining an image by photographing a surface of the electrode through illumination and an image sensor, and converting color information of the image into color coordinates. 15 【Claim 15】 The method of claim 9, wherein the reference value is derived from an average value of color coordinate values for a plurality of electrodes after manufacturing the plurality of electrodes. 20 【Claim 16】 36 The method of claim 9, wherein the reference value is derived from a profile of an electrode color coordinate value according to a residual solvent content in the electrode. 【Claim 17】 5 The method of claim 9, wherein the reference value is derived from a color coordinate value of an electrode satisfying an residual solvent content in a target electrode. 【Claim 18】 The method of claim 11, wherein it is determined that a dry state of the electrode is 10 defective when a difference between the measured color coordinate value and the reference value is 0.5 or more. 【Claim 19】 The method of claim 9, wherein a residual solvent content in the electrode of the 15 electrode determined as a good product is 1% by weight or less. 【Claim 20】 A method for manufacturing an electrode, the method comprising: a step of evaluating drying quality of an electrode according to a method of evaluating 20 the drying quality of the electrode according to claim 9; and 37 a step of rolling the electrode determined to be good.