Technical Field [1] Cross-Reference to Related Application [2] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0044900, filed on April 13, 2020, and Korean Patent Application No. 10-2020-0119926, filed on September 17, 2020, the disclosures of 5 which are incorporated herein by reference in their entirety. [3] Technical Field [4] The present invention relates to a method of evaluating the quality of an electrode and a method of manufacturing an electrode including evaluating the quality of the electrode thereby. 10 Background Art [5] Electrodes manufactured under the same recipe and process conditions should theoretically have the same properties, but in actual electrode manufacture, the properties may vary from batch to batch. Therefore, even among electrodes 15 manufactured under the same conditions, there may be defective electrodes, and the defective electrodes should be identified through an electrode quality inspection. [6] Adhesion, thickness, and loading amount are some of the commonly known electrode quality inspection items. Among these electrode quality inspection items, adhesion is an item for filtering out electrodes detached in an electrode assembly 20 process, electrodes peeled off in the activation process, and the like, and is a very important quality inspection item. [7] However, there are problems in that the adhesion of an electrode can only be evaluated after roll-pressing, and electrode quality cannot be evaluated in real time. [8] Therefore, there is a need to develop a method capable of filtering out 25 3 defective electrodes by evaluating the quality of electrodes through property evaluation before roll-pressing. Disclosure Technical Problem 5 [9] The present invention is directed to providing a method of evaluating electrode quality which is capable of simply and quickly filtering out defective electrodes among electrodes by the simple means of measuring a color coordinate value of the electrodes before roll-pressing. 10 Technical Solution [10] One aspect of the present invention provides a method of evaluating electrode quality, which includes: providing a plurality of electrodes which include a current collector and an active material layer formed on the current collector and have not been roll-pressed; measuring a color coordinate value of the active material layer of each of 15 the plurality of electrodes using an optical instrument and calculating an average value; and evaluating the electrodes as good products when a difference between the color coordinate value measured from the individual electrodes and the average value is no more than a predetermined value and as defective when the difference exceeds the predetermined value. 20 [11] Another aspect of the present invention provides a method of manufacturing an electrode, which includes: forming an active material layer by applying a slurry including an active material, a conductive material, and a binder onto a current collector and drying, and thus manufacturing a plurality of electrodes which have not been roll-pressed; evaluating the quality of the electrodes by the above-described 25 4 method; and roll-pressing an electrode evaluated as a good product. Advantageous Effects [12] A method of evaluating electrode quality according to the present invention is capable of simply and quickly filtering out defective electrodes among electrodes by 5 measuring a color coordinate value of the electrodes before roll-pressing. That is, it is possible to filter out defective electrodes even before roll-pressing, and therefore, it is possible to significantly reduce a defect rate of finished electrode products, which have been roll-pressed. 10 Best Mode of the Invention [13] Terms and words used in this specification and the claims should not be interpreted as being limited to commonly used meanings or meanings in dictionaries, and, based on the principle that the inventors can appropriately define concepts of terms in order to describe their invention in the best way, the terms and words should 15 be interpreted with meanings and concepts which are consistent with the technical spirit of the present invention. [14] It will be understood that terms such as “comprises,” “comprising,” “includes,” “including,” “has” or “having,” when used in the present specification, specify the presence of stated features, numbers, steps, components, or combinations thereof and 20 do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. [15] Hereinafter, the present invention will be described in detail. 25 5 [16] [17] A method of evaluating electrode quality according to the present invention includes: providing a plurality of electrodes which include a current collector and an active material layer formed on the current collector and have not been roll-pressed; measuring a color coordinate value of the active material layer of each of the plurality 5 of electrodes using an optical instrument and calculating an average value; and evaluating the electrodes as good products when a difference between the color coordinate value measured from the individual electrodes and the average value is no more than a predetermined value and as defective when the difference exceeds the predetermined value. 10 [18] When a color coordinate value of an active material layer of each of the plurality of electrodes which have not been roll-pressed is measured using the optical instrument and compared with the average value as described above, in the case of electrodes in which a difference between the color coordinate value measured from the 15 individual electrodes and the average value is within a predetermined value range, after the electrodes are roll-pressed, since the adhesion between a current collector and an active material layer is excellent, an adhesion defect may not occur. For example, when an electrode classified as a good product according to the present invention is roll-pressed, an adhesive strength of 20 gf/20 mm or more can be secured between a 20 current collector and an active material layer of the electrode. [19] According to the present invention, it is possible to simply and quickly filter out defective electrodes among electrodes by the simple means of measuring a color coordinate value of the electrodes before roll-pressing. That is, it is possible to filter out defective electrode even before roll-pressing, and therefore, it is possible to 25 6 significantly reduce a defect rate of finished electrode products, which have been roll-pressed. [20] Hereinafter, each step of the method of evaluating electrode quality according to the present invention will be described in more detail. 5 [21] Provision of plurality of electrodes which have not been roll-pressed [22] The present invention includes a step of providing a plurality of electrodes which include a current collector and an active material layer formed on the current collector and have not been roll-pressed. 10 [23] According to the present invention, the plurality of electrodes may be produced under the same recipe and process conditions. Theoretically, electrodes manufactured under the same recipe and process conditions should have the same properties, but in actual electrode manufacturing, the properties may vary from batch to batch. Therefore, even among electrodes manufactured under the same recipe and 15 process conditions, there may be defective electrodes, so the present inventors have implemented the present invention in order to filter out such defective electrodes simply and quickly. [24] The present invention does not evaluate electrodes that have been roll-pressed as in the conventional electrode quality evaluation but evaluates the quality of 20 electrodes that have not been roll-pressed, so defective electrodes can be filtered out before roll-pressing, and a defect rate after roll-pressing can be significantly reduced. [25] Measurement of color coordinate value of active material layer of each of plurality of electrodes and calculation of average value 25 7 [26] The present invention includes a step of measuring a color coordinate value of the active material layer of each of the electrodes using an optical instrument and calculating an average value. [27] The optical instrument is an instrument including a light source and an image sensor, and when an active material layer of each of the electrodes is analyzed using 5 the optical instrument, color information from the surface of the active material layer of each of the electrodes is converted into color coordinate values and detected. The image sensor is a device capable of converting incoming light into an electrical signal and may be, for example, a charge coupled device (CCD) sensor or a complementary metal-oxide-semiconductor (CMOS) sensor. 10 [28] According to the present invention, the optical instrument may be a spectrophotometer or a colorimeter. [29] The color coordinate value collectively refers to numerical values expressed as coordinates in a three-dimensional color space, and, for example, the color coordinate value may be an L* value, an a* value, a b* value, a whiteness value, or a 15 yellowness value. [30] According to the present invention, the color coordinate value of an active material layer may be measured by a contact colorimeter or a non-contact colorimeter. That is, the colorimeter may be a contact colorimeter or a non-contact colorimeter. In the case of using a non-contact colorimeter, since measurement is possible without 20 direct contact with a sample, measurement is convenient, and measurement can be performed in a continuous manufacturing process. [31] The color coordinate value of an active material layer may be measured, for example, using a CM2600d colorimeter manufactured by Konica Minolta, Inc. Specifically, the color coordinate value may be measured using a CM2600d 25 8 colorimeter manufactured by Konica Minolta, Inc., by setting the measurement mode to Specular Component Included (SCI) or Specular Component Excluded (SCE) and selecting a D65 standard light source (color temperature: 6,500 K) and the CIE 1976 10° standard observer, performing white correction, and then bringing the colorimeter into contact with a location to be measured. 5 [32] Evaluation of electrodes as good or defective through comparison of color coordinate values measured from individual electrodes with average values [33] The present invention includes a step of evaluating the electrodes as good products when a difference between the color coordinate value measured from the 10 individual electrodes and the average value is no more than a predetermined value and as defective when the difference exceeds the predetermined value. For example, when the predetermined value is 1 and the difference between the color coordinate value measured from the electrodes and the average value is 0.5, the electrodes are evaluated as good products, and when the difference between the color coordinate 15 value measured from the electrodes and the average value is 1.5, the electrodes are evaluated as defective. [34] When the difference between the color coordinate value measured from the individual electrodes and the average value is within a predetermined value range, since excellent adhesion between a current collector and an active material layer can 20 be secured after roll-pressing, a defect rate of finished electrode products, which have been roll-pressed, can be significantly reduced. [35] According to the present invention, when the color coordinate value is an L* value, the predetermined value may be 1 and preferably 0.5. [36] According to the present invention, when the color coordinate value is an a* 25 9 value, the predetermined value may be 0.02 and preferably 0.01. [37] According to the present invention, when the color coordinate value is a b* value, the predetermined value may be 0.06 and preferably 0.03. [38] According to the present invention, when the color coordinate value is a whiteness value, the predetermined value may be 0.7 and preferably 0.3. 5 [39] According to the present invention, when the color coordinate value is a yellowness value, the predetermined value may be 0.2. [40] Electrodes which are classified as good products as a result of the above-described comparison because differences between color coordinate values, that is, an L* value, an a* value, a b* value, a whiteness value, and a yellowness value, measured 10 from the individual electrodes and average color coordinate values satisfy the predetermined value ranges described above may have excellent electrode quality after roll-pressing. Specifically, electrodes classified as good products according to the electrode quality evaluation method of the present invention may exhibit excellent adhesion between a current collector and an active material layer after roll-pressing. 15 For example, an adhesive strength of 20 gf/20 mm or more can be secured between a current collector and an active material layer. [41] [42] A method of manufacturing an electrode according to the present invention 20 includes: forming an active material layer by applying a slurry including an active material, a conductive material, and a binder onto a current collector and drying, and thus manufacturing a plurality of electrodes which have not been roll-pressed; evaluating the quality of the electrodes by the above-described method; and roll-pressing an electrode evaluated as a good product. 25 10 [43] Hereinafter, each step of the method of manufacturing an electrode according to the present invention will be described in more detail. [44] Manufacture of plurality of electrodes which have not been roll-pressed 5 [45] The present invention includes a step of forming an active material layer by applying a slurry including an active material, a conductive material, and a binder onto a current collector and drying and thus manufacturing a plurality of electrodes which have not been roll-pressed. The active material layer may be formed on one or both sides of the current collector. 10 [46] The current collector is not particularly limited as long as it does not cause a chemical change in a battery and has conductivity, and in the case of a positive electrode current collector, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like may be used, and in the case of a negative 15 electrode current collector, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like, an aluminum-cadmium alloy, or the like may be used. [47] The current collector may typically have a thickness of 3 μm to 500 μm and 20 may have fine irregularities formed in a surface thereof to increase the adhesion of a positive electrode material or a negative electrode material. For example, the current collector may be used in any of various forms such as a film, a sheet, a foil, a net, a porous material, a foam, a non-woven fabric, and the like. [48] The slurry may be prepared by dissolving or dispersing an active material, a 25 11 conductive material, and a binder in a solvent. [49] When the active material is a positive electrode active material, the positive electrode active material is a compound enabling the reversible intercalation and deintercalation of lithium and, specifically, may include a lithium composite metal oxide including lithium and one or more transition metals such as cobalt, manganese, 5 nickel, or aluminum. More specifically, the lithium composite metal oxide may be 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., LiNi1-YMnYO2 (0