Specification Name of the invention: A strip type electrode used in a cylindrical jelly roll and a lithium secondary battery comprising the same Technical field [One] This application is an application for claiming priority for Korean Patent Application No. 10-2017-0148955 filed on November 09, 2017, and all contents disclosed in the specification and drawings of the application are incorporated herein by reference. [2] The present invention relates to a strip-shaped electrode used in a cylindrical jelly roll and a lithium secondary battery including the same. [3] Background [4] As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and among such secondary batteries, a lot of research has been conducted on lithium secondary batteries with high energy density and discharge voltage, and has been widely commercialized. Is being used. [5] Depending on the shape of the battery case, secondary batteries are classified into cylindrical and prismatic batteries in which an electrode assembly is embedded in a cylindrical or rectangular metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-shaped case of an aluminum laminate sheet. . [6] In addition, the electrode assembly built in the battery case is a charge/discharge power generator consisting of a stacked structure of a positive electrode/separator/cathode. And, it is roughly classified into a stack type in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked while interposed in a separator, and a stack/folding type in which the stacked unit cells are wound with a long separation film. Among them, the jelly roll type electrode assembly is the easiest to manufacture and has the advantage of high energy density per weight. [7] In the jelly roll electrode assembly, a strip-shaped electrode assembly including a structure in which a strip-shaped anode, a strip-shaped separator, and a strip-shaped cathode are stacked is wound in a cylindrical shape. [8] On the other hand, in recent years, as high capacity characteristics are required, it is necessary to manufacture a high-loading electrode. When the high-loading electrode of such a cylindrical battery is applied, a problem occurs because a crack occurs in the electrode coating layer at the core. [9] Detailed description of the invention Technical challenge [10] An object of the present invention is to provide a strip-type electrode and a lithium secondary battery including the same, which can improve cracks that may occur in the electrode coating layer of the core portion of the cylindrical jelly roll and prevent deterioration of the performance of the lithium secondary battery. [11] Means of solving the task [12] According to a first aspect of the present invention, a strip-shaped electrode assembly relates to a strip-shaped electrode used in a cylindrical jelly roll wound in a cylindrical shape such that a hollow is formed in a core portion, comprising: a strip-shaped electrode current collector; A first electrode active material layer formed on at least one surface of the strip-type electrode current collector; And a second electrode active material layer formed on the first electrode active material layer. A strip-shaped electrode is provided, which is formed to have a length shorter than the length in which the electrode active material layer is formed. [13] According to a second aspect of the present invention, in the first aspect, a strip-shaped electrode formed with a length shorter than the length of the strip-shaped electrode current collector so that a part of the surface of one side in the length direction of the strip-shaped electrode current collector is exposed to the outside Is provided. [14] According to a third aspect of the present invention, in the first aspect or the second aspect, a strip-shaped electrode formed in a ratio of 1:9 to 7:3 in a thickness of the first electrode active material layer and the second electrode active material layer is provided. do. [15] According to a fourth aspect of the present invention, in any one of the first to third aspects, the thickness of the first electrode active material layer and the second electrode active material layer is formed in a ratio of 3:7 to 6:4. A strip-shaped electrode is provided. [16] According to a fifth aspect of the present invention, a strip-type electrode assembly relates to a lithium secondary battery comprising a cylindrical jelly roll wound in a cylindrical shape so that a hollow is formed in a core portion, wherein the strip-type electrode assembly includes a strip-type anode , A strip-shaped separator and a strip-shaped negative electrode are sequentially stacked, and the strip-shaped positive electrode or the strip-shaped negative electrode is a strip-shaped electrode according to any one of the first to fourth aspects. A lithium secondary battery is provided. [17] According to a sixth aspect of the present invention, in the fifth aspect, the cylindrical jelly roll is wound so that one portion of the strip-shaped electrode assembly, where the first electrode active material layer is exposed, is located in the core portion of the cylindrical jelly roll. A lithium secondary battery is provided. [18] According to a seventh aspect of the present invention, in the fifth or sixth aspect, the lithium secondary battery further includes a center pin inserted in the core portion of the cylindrical jelly roll. [19] According to an eighth aspect of the present invention, in any one of the fifth to seventh aspects, the length of the surface on which the first electrode active material layer is exposed to the outside is 1 to 3 times the circumference of the center pin. A double lithium secondary battery is provided. [20] According to a ninth aspect of the present invention, in any one of the fifth to eighth aspects, each of the first electrode active material layer and the second electrode active material layer contains a binder, and the first electrode active material layer A lithium secondary battery is provided, wherein the contained binder and the binder contained in the second electrode active material layer are contained in a weight ratio of 90:10 to 60:40. [21] According to a tenth aspect of the present invention, in any one of the fifth to ninth aspects, a lithium secondary battery is provided, wherein the strip-shaped electrode is a strip-shaped positive electrode. [22] Effects of the Invention [23] The strip-shaped electrode of the present invention is formed of at least two electrode active material layers having different formation areas, and is wound around a strip-shaped electrode portion, for example, a center pin, located in the core portion of a cylindrical jelly roll 1 to 3 times. Since the strip-shaped electrode portion is formed to have a thinner thickness, the loading amount and the rolling rate in the core portion of the cylindrical jelly roll can be reduced, and ultimately, cracks in the strip-shaped electrode located in the core portion of the cylindrical jelly roll. It can be prevented from occurring. [24] In addition, since the strip-type electrode of the present invention is formed to have a relatively thick thickness by high loading except for a portion formed with a relatively thin thickness, it can meet the recent needs of a secondary battery having a high capacity characteristic. [25] In addition, according to an embodiment of the present invention, in a strip-type electrode having a high loading type, excellent bonding strength between the electrode current collector and the electrode active material layer may be exhibited, while excellent electrical conductivity of the lithium secondary battery may be maintained. [26] Brief description of the drawing [27] The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the content of the above-described invention, so the present invention is limited to the matters described in such drawings. It is limited and should not be interpreted. [28] 1 is a diagram schematically showing a cross-section of a strip-shaped electrode on which one electrode active material layer is formed according to the prior art. [29] FIG. 2 is a diagram schematically showing a top surface of a strip-shaped electrode on which one electrode active material layer is formed according to the prior art. [30] 3 is a schematic cross-sectional view of a strip-shaped electrode in which two electrode active material layers are formed according to an embodiment of the present invention. [31] FIG. 4 is a schematic view showing a top surface of a strip-shaped electrode on which a two-layer electrode active material layer is formed according to an embodiment of the present invention. [32] 5 is a schematic cross-sectional view of a strip-shaped electrode on which a three-layer electrode active material layer is formed according to another embodiment of the present invention. [33] 6 is a diagram schematically showing a top surface of a strip-shaped electrode on which a three-layer electrode active material layer is formed according to another embodiment of the present invention. [34] Best mode for carrying out the invention [35] Hereinafter, the present invention will be described in detail. The terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. Based on the principle that it should be interpreted as meanings and concepts consistent with the technical idea of ​​the present invention. [36] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to a conventional or dictionary meaning, and the inventors appropriately explain the concept of terms in order to explain their own invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention. Accordingly, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all the technical spirit of the present invention, and thus various alternatives that can be replaced at the time of application It should be understood that there may be equivalents and variations. [37] 1 and 2 are views schematically showing a cross-section and an upper surface of a strip-shaped electrode on which an electrode active material layer according to the prior art is formed. [38] 1 and 2, a single electrode active material layer 12 having a uniform thickness is formed on the strip-type electrode current collector 11. When a cylindrical jelly roll is later manufactured with such a strip-shaped electrode 10, cracks may occur in the electrode active material layer at a portion corresponding to the core portion of the cylindrical jelly roll. This problem tends to be worsened when the electrode active material layer has a thicker loading electrode. [39] 3 and 4 are views schematically showing a cross-section and an upper surface of a strip-shaped electrode on which two electrode active material layers are formed according to an exemplary embodiment of the present invention. [40] 3 and 4, the strip-shaped electrode 100 according to an aspect of the present invention is a strip-shaped electrode assembly used in a cylindrical jelly roll wound in a cylindrical shape so that a hollow is formed in the core portion. Regarding the electrode 100, the strip-type electrode current collector 110; A first electrode active material layer 120 formed on at least one surface of the strip-type electrode current collector 110; And a second electrode active material layer 130 formed on the first electrode active material layer 120, wherein the second electrode active material layer 130 comprises one side of the first electrode active material layer 120 in a length direction It is characterized in that the first electrode active material layer 120 is formed to have a length shorter than the length at which a portion of the surface is exposed to the outside. [41] According to the present invention, since two electrode active material layers having different formation areas are formed, the coating thickness of the electrode active material layer of the strip-shaped electrode portion located in the core portion of the cylindrical jelly roll can be formed to be thin, thereby , By reducing the loading amount and rolling rate in the core portion of the cylindrical jelly roll, it is possible to prevent the occurrence of cracks in the core portion. [42] In one embodiment of the present invention, the first electrode active material layer 120 includes the strip-type electrode current collector 110 so that a part of the surface of one side in the length direction of the strip-type electrode current collector 110 is exposed to the outside. It may be formed in a length shorter than the length of. An electrode tab may be attached to the surface of the strip-type electrode current collector 110 exposed to the outside to be formed. [43] Meanwhile, in an embodiment of the present invention, the thickness of the first electrode active material layer 120 and the second electrode active material layer 130 is in a ratio of 1:9 to 7:3 or 3:7 to 6:4. Can be formed. When the thickness of the first electrode active material layer is formed too thin below the ratio, there is a problem that the coating processability of the electrode active material layer may be deteriorated, and the thickness of the first electrode active material layer exceeds the ratio so that it is too thick. When formed, the effect of improving cracks in the cylindrical jelly roll core portion may be reduced, which is not preferable. [44] Meanwhile, the total thickness of the first electrode active material layer and the second electrode active material layer may be similar to that of a general electrode active material layer, and more specifically, the total thickness of the electrode active material layer may be 10 to 300 μm. [45] In addition, the strip-shaped electrode may be a positive electrode or a negative electrode, and is particularly preferable in an electrode to which an active material is loaded. The electrode into which the active material is loaded may be a positive electrode. [46] In this case, the positive electrode, the negative electrode, and the separator constituting the electrode assembly are manufactured by a conventional method, and all of those used in manufacturing a lithium secondary battery may be used. [47] In one embodiment of the present invention, the positive electrode may be manufactured by forming a first positive electrode active material layer and a second positive electrode active material layer on the positive electrode current collector to form a step. That is, a slurry for the first positive electrode active material layer including a positive electrode active material, a binder, a conductive material, and a solvent, and a second positive electrode active material layer for the first positive electrode active material layer including a positive electrode active material, a binder, a conductive material, and a solvent. Preparation of the slurry for each, coating the slurry for the first positive electrode active material layer on the electrode current collector, drying and rolling, and the second positive electrode active material layer to be shorter than the length of the first electrode active material layer is formed The slurry for is coated on the first positive electrode active material layer, dried, and rolled to prepare a positive electrode. [48] The positive electrode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. , Nickel, titanium, silver, or the like may be used. [49] In addition, the positive electrode active material may include a lithium transition metal oxide represented by Formula 1 below. [50] [Formula 1] [51] Li(Ni a Co b Mn c )O 2 [52] In Formula 1, [53] 0.55≤a≤0.9, 0.05≤b≤0.22, 0.05≤c≤0.23, and a+b+c=1. [54] Representative examples of such a positive electrode active material include Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 , or Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 . [55] In addition, the positive electrode active material includes lithium-manganese oxides (eg, LiMnO 2 , LiMn 2 O 4, etc.), lithium-cobalt oxides (eg, LiCoO 2 etc.), lithium-nickel oxide (eg, LiNiO 2 ), lithium-nickel-manganese oxide (eg, LiNi 1 - Y Mn Y O 2 (here, 0