Title of Invention: High-nickel electrode sheet with reduced reactivity with moisture and manufacturing method thereof technical field [One] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0054235 on May 7, 2020 and Korean Patent Application No. 10-2021-0049862 on April 16, 2021. All disclosures are incorporated herein by reference. [2] The present invention relates to a positive electrode comprising a positive electrode active material having a high nickel content, a positive electrode sheet, and a method for manufacturing the same. The present invention relates to an electrode sheet in which reactivity with moisture is suppressed by applying a slurry for a second positive electrode mixture containing a positive electrode active material having strong particle strength, and a method for manufacturing the same. background [3] In a lithium secondary battery, an organic electrolyte or a polymer electrolyte is charged between a positive electrode and a negative electrode made of an active material capable of intercalation and deintercalation of lithium ions, and lithium ions are intercalated/deintercalated from the positive electrode and the negative electrode. Electric energy is produced by a reduction reaction with [4] As a positive active material of a lithium secondary battery, lithium cobalt oxide (LiCoO 2), lithium nickel oxide (LiNiO 2), lithium manganese oxide (LiMnO 2 or LiMn 2O 4, etc.), lithium iron phosphate compound (LiFePO 4), etc. were used. In addition, as a method for improving low thermal stability while maintaining the excellent reversible capacity of LiNiO 2 , a lithium composite metal oxide in which a part of nickel (Ni) is substituted with cobalt (Co) and manganese (Mn) (hereinafter simply referred to as ‘NCM-based Lithium composite transition metal oxide') was developed. However, the conventionally developed NCM-based lithium composite transition metal oxide has insufficient capacity characteristics, so there is a limit to its application. [5] In order to improve this problem, recently, research to increase the content of nickel in the NCM-based lithium composite transition metal oxide is being made. As the content of nickel increases, the energy density per volume increases, but in the case of a high-concentration nickel positive electrode active material, there is a problem in that the structural stability and chemical stability of the active material are deteriorated, so that thermal stability is rapidly reduced. In addition, nickel ions are irreversibly converted to NiO by reacting with moisture and carbon dioxide present in the storage environment, and as lithium ions escape in this process, lithium by-products present in the form of LiOH and Li 2CO 3 increase, Due to this, there are problems in increasing the resistance of the active material surface, reducing the capacity of the battery, and increasing gas generation during high temperature storage. [6] In general, after applying the slurry for electrode mixture containing the electrode active material on the current collector sheet, the dried and rolled electrode sheet is wound around the core until the electrode is punched for assembling the battery in a wound state. are kept 1 shows the electrode sheet 10 in a wound state for storage. At this time, based on the width direction (arrow) of the electrode sheet, the moisture permeation is easier at both ends (A) than the central part (B) of the holding part, and the moisture content is high by that amount. Therefore, in the case of the positive electrode sheet including the positive electrode active material of the NCM-based lithium composite transition metal oxide, there is a high probability that nickel and moisture react at both end portions compared to the central portion. [7] Accordingly, in order to alleviate moisture content during the manufacture of a high-nickel positive electrode active material electrode having a high nickel content, Japanese Patent Application Laid-Open No. 2019-149269 discloses a first positive electrode active material having a nickel content of 50% to 80% in the central portion. A secondary battery including a positive electrode to which a second positive electrode active material having a nickel content of 20% to 40% is applied to both ends thereof. However, the conventional technique has an effect of suppressing the precipitation of lithium, but is not sufficient to improve the life performance of the battery, and the second positive active material applied to both ends contains only 20% to 40% of nickel, There have been difficulties in realizing the desired energy density. [8] Therefore, in a positive electrode having a high nickel content, it is necessary to develop a technology for a battery capable of realizing a high energy density and suppressing a reaction with moisture. DETAILED DESCRIPTION OF THE INVENTION technical challenge [9] The present invention was devised to solve the above problems, and specifically, in an electrode sheet wound in a roll, the positive electrode active material having a high nickel content alleviates the reaction with moisture, and an electrode capable of realizing a high energy density An object of the present invention is to provide a sheet and a method for manufacturing the same. means of solving the problem [10] The electrode sheet of the present invention for solving the above problems is an electrode sheet comprising a holding portion and an uncoated portion coated with a positive electrode mixture layer on at least one surface of a current collector, wherein the holding portion is formed in a central portion along the longitudinal direction of the electrode sheet and a first positive electrode mixture layer comprising a positive electrode active material of lithium nickel oxide; and a second positive electrode mixture layer formed on one or both edges of the first positive electrode mixture layer and including a positive electrode active material of lithium nickel oxide, wherein the positive electrode active material particle strength in the second positive electrode mixture layer is, It is characterized in that it is greater than the particle strength of the positive active material in the layer. [11] In one specific example, the width length of the second positive electrode mixture layer is 1 to 15% of the width length of the first positive electrode mixture layer. [12] In one specific example, each of the positive electrode active materials included in the first positive electrode mixture layer and the second positive electrode mixture layer each independently includes a compound represented by Formula 1 below. [13] [Formula 1] [14] Li aNi 1-x-yCo xM1 yM2 wO 2 [15] (In Formula 1, 1.0≤a≤1.5, 0≤x≤0.2, 0≤y≤0.2, 0≤w≤0.1 and 0≤x+y≤0.4, [16] M1 includes any one or both selected from the group consisting of Mn and Al, and M2 is any one or two or more elements selected from the group consisting of Ba, Ca, Zr, Ti, Mg, Ta, Nb, and Mo. including) [17] In one specific example, the ratio (B/A) of the particle strength (B) of the positive electrode active material in the second positive electrode mixture layer to the particle strength (A) of the positive electrode active material in the first positive electrode mixture layer is 1.01 to 1.5. [18] In one specific example, the second positive electrode mixture layer may include a first positive electrode active material having a relatively large average particle size (D 50 ) and a second positive electrode having a relatively small average particle size (D 50 ). mixtures of active materials. [19] In one specific example, the first positive active material has an average particle size (D 50 ) of 9 μm to 30 μm, and the second positive active material has an average particle size (D 50 ) of less than 9 μm. [20] In one specific example, in the second positive electrode mixture layer, a mixing ratio of the first positive active material and the second positive active material is 95:5 to 65:35 by weight. [21] In one specific example, the positive electrode active material of the first positive electrode mixture layer may be composed of a positive electrode active material having the same average particle size (D 50 ). [22] In this case, the positive electrode active material of the first positive electrode mixture layer has an average particle size (D 50) of 9 μm to 30 μm. [23] In one specific example, the first positive electrode mixture layer includes a first positive electrode active material having a relatively large average particle size (D 50 ) and a second positive electrode having a relatively small average particle size (D 50 ). It may also contain mixtures of active materials. [24] In this case, the first positive active material may have an average particle size (D 50) of 9 μm to 30 μm, and the second positive active material may have an average particle size (D 50) of less than 9 μm. [25] In this case, the ratio (b/a) of the weight (b) of the second positive electrode active material to the weight (a) of the first positive electrode active material in the second positive electrode material mixture layer is: It is greater than the ratio (b'/a') of the weight (b') of the second positive electrode active material to the weight (a') of [26] The lithium secondary battery of the present invention includes a positive electrode in which the holding part and the uncoated part of the electrode sheet are punched out according to the shape and size of the unit electrode. [27] A method of manufacturing an electrode sheet according to the present invention includes: a slurry preparation process of preparing a slurry for a first positive electrode mixture and a slurry for a second positive electrode mixture, respectively; a coating process of forming a first positive electrode mixture layer and a second positive electrode mixture layer by applying the first positive electrode mixture slurry and the second positive electrode mixture slurry on the current collector sheet; drying process; and a rolling process, wherein in the coating process, the first positive electrode mixture slurry is at the center of the electrode sheet, and the second positive electrode mixture slurry is the first positive electrode mixture slurry based on the width direction of the electrode sheet. Having a predetermined width on one or both edges, applied in the longitudinal direction of the electrode sheet, the second positive electrode mixture slurry includes a first positive electrode active material having a relatively large average particle size (D 50) and a large particle diameter, and average particles The size (D 50 ) includes a mixture of the second positive electrode active material having a relatively small particle diameter. [28] In one specific example, the width length of the second positive electrode mixture layer in the coating process is 1 to 15% of the width length of the first positive electrode mixture layer. Effects of the Invention [29] In the electrode sheet according to the present invention, in the second positive electrode mixture layer at both edges of the electrode sheet holding part, which is easy to be exposed to moisture and where particle crumbling can occur relatively well due to the rolled roll having a worn structure, the first By including the positive electrode active material having a greater particle strength than the positive electrode mixture layer, the reaction of the nickel component of the second positive electrode mixture layer with moisture after rolling is minimized, thereby improving the lifespan characteristics of the battery. [30] In addition, the electrode sheet according to the present invention is applied to a high-nickel positive electrode material having a high energy density, and there is also an advantage in that the capacity characteristics of the battery are improved. Brief description of the drawing [31] 1 is a schematic diagram of an electrode sheet in a wound state. [32] 2 is a graph showing the moisture content in the electrode according to the electrode manufacturing step. [33] 3 is a schematic diagram showing a rolling roller with wear on both ends as the number of uses increases; am. [34] 4 is a schematic plan view showing an example of an electrode sheet according to an embodiment of the present invention. [35] 5 is a graph showing the results of measuring the capacity retention rate according to the charge/discharge cycle for the batteries of Examples and Comparative Examples of the present invention. Best mode for carrying out the invention [36] Hereinafter, the present invention will be described in detail. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention based on the principle that it can be defined in [37] [38] An electrode sheet according to an embodiment of the present invention is an electrode sheet comprising a holding part and an uncoated part coated with a positive electrode mixture layer on at least one surface of a current collector, wherein the holding part is formed in a central part along a longitudinal direction of the electrode sheet, a first positive electrode mixture layer including a positive electrode active material of lithium nickel oxide; and a second positive electrode mixture layer formed on one or both edges of the first positive electrode mixture layer and including a positive electrode active material of lithium nickel oxide, wherein the positive electrode active material particle strength in the second positive electrode mixture layer is, It is characterized in that it is greater than the particle strength of the positive active material in the layer. [39] 2 is a graph showing the moisture content in the electrode according to the electrode manufacturing step. Referring to this graph, it can be seen that the moisture content in the electrode is greatly increased immediately after the rolling process. This is because, as the electrode is rolled with a large force, the active material particles in the electrode layer are crushed, and the specific surface area of ​​the active material is rapidly increased. [40] In addition, the rolling roller for rolling the electrode sheet may have a high rolling ratio at both ends of the roller due to causes such as structure or wear. 3 shows the shape of the rolling roller 20 due to wear, the central portion 20a of the roller has a structure that is more worn compared to both ends 20b of the roller, and in the rolling roller of this structure, Both end portions may have a greater rolling rate than the central portion. Accordingly, the portion corresponding to both ends of the roller in the electrode sheet receives more force during rolling than the portion corresponding to the center portion of the roller, so the active material particles may be more brittle by that amount, and thus the specific surface area of ​​the active material particles can become vulnerable to moisture. Moreover, in the electrode sheet in the form of being wound into a roll for storage of the electrode sheet, the corresponding portion is to both end portions in the width direction, since the penetration of moisture from the outside can be facilitated, thus further exacerbating the moisture vulnerability. [41] In this way, both ends of the electrode sheet in the width direction are easier to contact with moisture due to their position compared to the central part, and there is a possibility that the rolling rate is relatively high due to the influence of the worn rolling rollers, and the reaction between the active material and moisture It is an environment of increasing area. Therefore, in manufacturing a positive electrode or positive electrode sheet having a high nickel content, which is vulnerable to moisture, by including a positive electrode active material having a particle strength relatively stronger to rolling than a central portion in both end portions in the width direction of the electrode sheet, At both ends, the reaction between nickel and moisture was minimized. [42] Referring to FIG. 4 , the electrode sheet of the present invention includes a holding part 100 and an uncoated part 200 coated with a positive electrode mixture layer on at least one surface of a current collector, and the holding part 100 includes an electrode sheet. It consists of a first positive electrode mixture layer 110 formed in a central portion along the longitudinal direction (y-axis) of , and a second positive electrode mixture layer 120 formed on both edges of the first positive electrode mixture layer 110 . Here, both sides refer to both edges with respect to the width direction (x-axis) of the electrode sheet. 4 illustrates an embodiment in which the second positive electrode mixture layer is formed on both edges of the first positive electrode mixture layer, but is not limited thereto, and the second positive electrode mixture layer may be formed on one edge region of the first positive electrode mixture layer. there is. [43] In the electrode sheet of the present invention, the particle strength of the positive electrode active material included in the second positive electrode mixture layer is greater than the particle strength of the positive electrode active material in the first positive electrode mixture layer. By including the positive electrode active material having a relatively large particle strength in the second positive electrode mixture layer as described above, the magnitude of the force applied to the second positive electrode mixture layer during rolling due to the abrasion of the rolling roller is increased by the amount of force applied to the first positive electrode mixture layer. Even if it is larger than the magnitude of the force, the degree of particle breakage of the second positive electrode mixture layer is similar to or smaller than that of the first positive electrode mixture layer, and the increase in the specific surface area of ​​the active material particles is suppressed by that amount. This will minimize the reactivity with water. [44] In the present invention, the particle strength may be defined as compressive fracture strength. A cathode active material for a secondary battery is subjected to a rolling process as one of the manufacturing processes. The rolling process means pressing the active material layer several times with a predetermined pressure in order to increase the density and increase the crystallinity. During the rolling process, some particles of the cathode active material may be broken without overcoming the compressive stress received during rolling, and thus the particles may be destroyed. When a force is applied to the cathode active material particles, the particle strength can be quantified by measuring the force at the point in time when the cracks occur in the particles. For example, the particle strength is measured by measuring the point at which the particles crack (crack) by applying pressure to the positive active material with a force of 0.5 to 10 mN using a micro compression tester (Equipment for Electronic Components Research Institute). It may be a value converted to . [45] In one specific example, the range of the particle strength of the positive electrode active material of the second positive electrode mixture layer may be 30 to 300 MPa, more preferably 40 to 200 MPa, more preferably 50 to 150 MPa. can In addition, the particle strength of the positive electrode active material of the first positive electrode mixture layer, within a range smaller than the particle strength of the positive electrode active material of the second positive electrode mixture layer, may be 30 to 300 MPa, more preferably 40 to 200 MPa and more preferably 50 to 150 MPa. [46] In one specific example, the ratio (B/A) of the positive electrode active material particle strength (B) in the second positive electrode mixture layer to the positive electrode active material particle strength (A) in the first positive electrode mixture layer may be greater than 1 and 2.0 or less and may preferably be 1.01 to 1.5, and more preferably 1.1 to 1.4. [47] In one specific example, the second positive electrode mixture layer includes a first positive electrode active material having a relatively large average particle size (D 50 ) and a second positive electrode active material having a relatively small average particle size (D 50 ). contains a mixture of The second positive electrode mixture layer in which the positive electrode active material of large particle diameter and small particle diameter are mixed is filled with the second positive electrode active material of small particle diameter in the pores formed by particles of the first positive electrode active material of large particle diameter, so that the first positive electrode active material of large particle diameter It can be stronger for the same compressive stress as compared to the case composed only of particles. The present invention applies a blending system of a first positive electrode active material having a large particle diameter and a second positive electrode active material having a small particle diameter to the second positive electrode mixture layer, so that the particle strength of the active material of the second positive electrode mixture layer is determined by the particles of the first positive electrode mixture layer active material greater than the strength. [48] In one specific example, the first positive active material may have an average particle size (D 50) of 9 μm to 30 μm, preferably 9 to 25 μm, more preferably 10 to 20 μm, and the second The positive active material may have an average particle size (D 50) of less than 9 μm, preferably 1 to 8 μm, and more preferably 2 to 7 μm. [49] And, in the present invention, the average particle size D 50 may be defined as a particle size corresponding to 50% of the cumulative volume in the particle size distribution curve. The average particle diameter D 50 may be measured using, for example, a laser diffraction method. For example, in the method of measuring the average particle size (D 50) of the positive active material, the particles of the positive active material are dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (eg, Microtrac MT 3000). After irradiating ultrasonic waves of about 28 kHz with an output of 60 W, the average particle diameter D 50 corresponding to 50% of the volume accumulation amount in the measuring apparatus can be calculated. [50] In one specific example, each of the positive electrode active materials included in the first positive electrode mixture layer and the second positive electrode mixture layer each independently includes a compound represented by Formula 1 below. [51] [Formula 1] [52] Li aNi 1-x-yCo xM1 yM2 wO 2 [53] (In Formula 1, 1.0≤a≤1.5, 0≤x≤0.2, 0≤y≤0.2, 0≤w≤0.1 and 0≤x+y≤0.4, [54] M1 includes any one or both selected from the group consisting of Mn and Al, and M2 is any one or two or more elements selected from the group consisting of Ba, Ca, Zr, Ti, Mg, Ta, Nb, and Mo. including) [55] When it has the composition represented by the above formula (1), it can exhibit excellent capacity characteristics along with excellent structural stability. [56] Specifically, in the lithium nickel oxide represented by Formula 1, Li may be included in an amount corresponding to a, that is, 1.0≤a≤1.5. If a is less than 1.0, there is a fear that the capacity may decrease, and if it exceeds 1.5, the particles are sintered in the firing process, which may make it difficult to manufacture the active material. Considering the remarkable effect of improving the capacity characteristics of the positive electrode active material according to the control of the Li content and the balance of sinterability during the production of the active material, Li is more specifically 1.0≤a≤1.2, and more specifically 1.0≤a≤1.15. may be included. [57] In addition, in the lithium nickel oxide represented by Formula 1, Ni may be included in a content corresponding to 1-x-y, that is, a content of 0.6≤1-x-y≤1. If 1-x-y is less than 0.6, there is a risk that the capacity characteristics may be deteriorated, and if it exceeds 1, there is a risk of deterioration in high-temperature stability.There are concerns. Considering the remarkable effect of improving the capacity characteristics according to the inclusion of Ni, Ni may be included in a content of 0.8≤1-x-y<1, more specifically, 0.8≤1-x-y<0.95. [58] In addition, in the lithium nickel oxide represented by Formula 1, M1 may be at least one selected from the group consisting of Al and Mn, and more specifically, may be Al or Mn. The M1 may be included in a content corresponding to y, that is, a content of 0≤y≤0.2. When y exceeds 0.2, there is a fear that the output characteristics and capacity characteristics of the battery are rather deteriorated. Considering the remarkable effect of improving battery characteristics due to the inclusion of element M1, M1 may be more specifically included in a content of 0 Particle strength of the active material of the first positive electrode mixture layer? Capacity retention at 500 cycles (%) Example 1 0 91.9 Example 2 0 90.6 Example 3 O 91.2 Example 4 0 89.0 Comparative Example 1 X 87.5 Comparative Example 2 X 87 [146] Referring to Table 1 and Figure 5, the secondary battery according to the embodiment of the present invention has an excellent capacity retention rate compared to the battery of the comparative example, which is a positive electrode to which a positive electrode active material of lithium nickel oxide is applied. It is judged that this is due to the effect of suppressing the reactivity of the nickel component with moisture by differently controlling the particle strengths of the second positive electrode mixture layer and each positive electrode active material included in the first positive electrode mixture layer. [147] [148] As seen through the above, drawings, examples, etc.The invention has been described in more detail. However, the configuration described in the drawings or embodiments described in the present specification is only one embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various equivalents and It should be understood that there may be variations. Claims [Claim 1] An electrode sheet comprising a holding part and an uncoated part coated with a positive electrode mixture layer on at least one surface of a current collector, wherein the holding part is formed in a central part along the length direction of the electrode sheet, and comprising a positive electrode active material of lithium nickel oxide 1 positive electrode mixture layer; and a second positive electrode mixture layer formed on one or both edges of the first positive electrode mixture layer and including a positive electrode active material of lithium nickel oxide, wherein the positive electrode active material particle strength in the second positive electrode mixture layer is, An electrode sheet, characterized in that it is greater than the particle strength of the positive electrode active material in the layer. [Claim 2] The electrode sheet according to claim 1, wherein a width of the second positive electrode mixture layer is 1 to 15% of a width of the first positive electrode mixture layer. [Claim 3] The electrode sheet according to claim 1, wherein each of the positive electrode active materials included in the first positive electrode mixture layer and the second positive electrode mixture layer each independently includes a compound represented by the following Chemical Formula 1. [Formula 1] Li aNi 1-x-yCo xM1 yM2 wO 2 (In Formula 1, 1.0≤a≤1.5, 0≤x≤0.2, 0≤y≤0.2, 0≤w≤0.1 and 0≤x+y ≤0.4, M1 includes any one or both selected from the group consisting of Mn and Al, and M2 is any one selected from the group consisting of Ba, Ca, Zr, Ti, Mg, Ta, Nb, and Mo or contains two or more elements) [Claim 4] According to claim 1, wherein the ratio (B / A) of the positive electrode active material particle strength (B) in the second positive electrode mixture layer to the positive electrode active material particle strength (A) in the first positive electrode mixture layer is 1.01 to 1.5 Characterized in the electrode sheet. [Claim 5] The method of claim 1, wherein the second positive electrode mixture layer comprises a first positive electrode active material having a relatively large average particle size (D 50) and a second positive electrode having a relatively small average particle size (D 50). An electrode sheet comprising a mixture of active materials. [Claim 6] The method according to claim 5, wherein the first positive active material has an average particle size (D 50) of 9 μm to 30 μm, and the second positive active material has an average particle size (D 50) of less than 9 μm. electrode sheet. [Claim 7] The electrode sheet according to claim 5, wherein in the second positive electrode mixture layer, a mixing ratio of the first positive active material and the second positive active material is 95:5 to 65:35 by weight. [Claim 8] The electrode sheet according to claim 5, wherein the positive electrode active material of the first positive electrode mixture layer is composed of a positive electrode active material having the same average particle size (D 50). [Claim 9] The electrode sheet according to claim 8, wherein the positive electrode active material of the first positive electrode mixture layer has an average particle size (D 50) of 9 μm to 30 μm. [Claim 10] The method of claim 7, wherein the first positive electrode mixture layer comprises a first positive electrode active material having a relatively large average particle size (D 50) and a second positive electrode having a relatively small average particle size (D 50). An electrode sheet comprising a mixture of active materials. [Claim 11] The method of claim 10, wherein the ratio (b/a) of the weight (b) of the second positive electrode active material to the weight (a) of the first positive electrode active material in the second positive electrode mixture layer is: An electrode sheet, characterized in that the ratio (b′/a′) of the weight (b′) of the second positive electrode active material to the weight (a′) of the first positive electrode active material is greater than (b′/a′). [Claim 12] The method according to claim 10, wherein the first positive active material has an average particle size (D 50) of 9 μm to 30 μm, and the second positive active material has an average particle size (D 50) of less than 9 μm. electrode sheet. [Claim 13] A lithium secondary battery comprising a positive electrode in which the holding part and the uncoated part of the electrode sheet according to claim 1 are punched out according to the shape and size of a unit electrode. [Claim 14] A method of manufacturing the electrode sheet according to claim 1, comprising: a slurry preparation process of preparing a slurry for a first positive electrode mixture and a slurry for a second positive electrode mixture, respectively; a coating process of forming a first positive electrode mixture layer and a second positive electrode mixture layer by applying the first positive electrode mixture slurry and the second positive electrode mixture slurry on the current collector sheet; drying process; and a rolling process, wherein in the coating process, the first positive electrode mixture slurry is at the center of the electrode sheet, and the second positive electrode mixture slurry is the first positive electrode mixture slurry based on the width direction of the electrode sheet. The slurry for the second positive electrode mixture having a predetermined width on one or both edges of the electrode sheet and applied in the longitudinal direction includes a first positive electrode active material having a relatively large average particle size (D 50) and a large particle diameter, and average particles A method of manufacturing an electrode sheet comprising a mixture of a second positive electrode active material having a relatively small size (D 50 ). [Claim 15] 15. The method of claim 14, wherein the width of the second positive electrode mixture layer in the coating process is 1 to 15% of the width of the first positive electrode mixture layer.