Title of Invention: Electrode assembly and manufacturing method thereof technical field [One] Cross Citation with Related Applications [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0027431 dated March 04, 2020, and all contents disclosed in the documents of the Korean patent application are incorporated as a part of this specification. [3] technical field [4] The present invention relates to an electrode assembly and a method for manufacturing the same, and more particularly, to an electrode assembly and method for manufacturing the same, which prevents the electrode from being damaged such as wrinkles or swells on the electrode due to the taping process, or the active material of the electrode is detached. is about background [5] In general, types of secondary batteries include a nickel cadmium battery, a nickel hydrogen battery, a lithium ion battery, and a lithium ion polymer battery. These secondary batteries are not only used in small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, Portable Game Devices, Power Tools and E-bikes, but also in large products requiring high output such as electric and hybrid vehicles and surplus power generation. It is also applied and used in power storage devices that store power or renewable energy and power storage devices for backup. [6] In order to manufacture a secondary battery, an electrode assembly is accommodated in a battery case, an electrolyte is injected, and then sealed. And in order to manufacture the electrode assembly, first, a positive electrode active material slurry is applied to a positive electrode current collector, and a negative electrode active material slurry is applied to a negative electrode current collector to prepare a positive electrode and a negative electrode. An electrode assembly is manufactured by placing a separator between the positive electrode and the negative electrode, and these electrode assemblies are classified into various types. For example, a simple stack type in which positive electrodes, separators, and negative electrodes are continuously stacked by crossing each other without manufacturing a unit cell, a unit cell is first manufactured using positive electrodes, separators, and negative electrodes, and then these unit cells Lamination & Stack Type (L&S, Lamination & Stack Type), a stack and folding type in which a plurality of unit cells are attached to one side of a long separator film at regular intervals and repeatedly folded in the same direction from one end of the separator film (S&F, Stack & Folding Type), etc. [7] FIG. 1 is a perspective view of a conventional electrode assembly 30 , and FIG. 2 is a front view of the conventional electrode assembly 30 . [8] The conventional simple stack type or lamination-and-stack type electrode assembly 30 has a simple structure and a high electrolyte impregnation degree, but has a problem in that the production speed is slow and the alignment degree is lowered. In order to maintain the alignment of the plurality of stacked electrodes and separators of the electrode assembly 30 , a taping process is performed. Then, as shown in FIG. 1 , the tape 31 is attached to both sides and a portion of the upper and lower surfaces of the electrode assembly 30 . [9] However, in the simple stack type or lamination and stack type electrode assembly 30 , the negative electrode and the separator are relatively wider than the positive electrode. Therefore, since the peripheral portion protrudes outward, if the tape 31 is attached, there is a problem in that the electrode is damaged, such as wrinkles or swells on the electrode, or the active material of the electrode is detached. [10] In addition, the tape 31 may be detached later in the electrolyte injection process or the degassing process. In particular, in the degassing process, since the gas inside the case must be discharged to the outside, there is a problem in that the tape 31 may be more easily detached by the flow of the gas. [11] On the other hand, the stack-and-folding type electrode assembly has a high production speed and high structural stability, but has a problem in that the process is complicated and the degree of alignment and the degree of impregnation of the electrolyte are deteriorated. DETAILED DESCRIPTION OF THE INVENTION technical challenge [12] SUMMARY OF THE INVENTION An object of the present invention is to provide an electrode assembly and a method of manufacturing the same for preventing the electrode from being damaged, such as wrinkles or swells on the electrode due to the taping process, or the active material of the electrode is detached. [13] The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. means of solving the problem [14] An electrode assembly according to an embodiment of the present invention for solving the above problems includes: a first electrode formed in a single sheet shape, in-folding and out-folding are repeated at regular intervals; a second electrode formed in a plurality of pieces and interposed in a space formed by folding the first electrode; and a separator formed in a single sheet shape, interposed between the first electrode and the second electrode, in which in-folding and out-folding are repeated at regular intervals with the first electrode, wherein the first electrode comprises: The first electrode collector is a single-sided electrode in which the first electrode active material is applied only on one surface, and the second electrode is a double-sided electrode in which the second electrode active material is applied to both surfaces of the second electrode collector. [15] In addition, the second electrode may be interposed only in a space formed by in-folding of the first electrode. [16] In addition, the separator may be interposed between one surface of the first electrode on which the first electrode active material is applied and the second electrode. [17] In addition, the first electrode may have an insulating portion formed in the shape of a single film on the other surface on which the separator is not interposed. [18] In addition, the insulating part may include at least one of polyethylene terephthalate (PET), polypropylene (PP), and polytetrafluoroethylene (PTFE). [19] An electrode assembly manufacturing method according to an embodiment of the present invention for solving the above problems includes: stacking a separator formed in a single sheet shape on one surface of a first electrode formed in a single sheet shape in the same direction; forming an electrode stack by seating the second electrodes formed of a plurality of pieces to be spaced apart from each other at regular intervals on the separator; and folding the electrode stack by in-folding and out-folding the first electrode and the separator, wherein the first electrode has a cross-section in which a first electrode active material is applied to only one surface of a first electrode current collector. The electrode is an electrode, and the second electrode is a double-sided electrode in which a second electrode active material is applied to both surfaces of a second electrode current collector. [20] In addition, in the step of stacking the separator, the separator may be stacked on one surface of the first electrode on which the first electrode active material is applied. [21] In addition, the predetermined interval may be formed to be longer than a length of the second electrode. [22] In addition, before the step of folding the electrode stack, the method may further include forming an insulating part by applying an insulating material on the other surface of the first electrode to which the first electrode active material is not applied, and then drying the insulating material. [23] In addition, the step of forming the insulating part may be performed before the step of seating the second electrode. [24] In addition, in the folding of the electrode stack, in the first electrode and the separator, regions at which one end of the second electrode is located are each in-folded, and regions at which the other end of the second electrode is located are out-folded, respectively. can [25] Other specific details of the invention are included in the detailed description and drawings. Effects of the Invention [26] According to the embodiments of the present invention, there are at least the following effects. [27] Since the first electrode is formed in a single sheet shape, there is no need to be fixed to the electrode assembly with a tape, and thus, it is possible to prevent damage to the electrode such as wrinkles or swells in the electrode, or the active material of the electrode is detached. [28] In addition, since the first electrode is a single-sided electrode, an unnecessary electrode active material is not formed in the outermost portion of the electrode assembly, so that the energy density to volume ratio can be improved. [29] In addition, since it is not necessary to manufacture the unit cell first, the continuous process is easy, thereby saving process time. [30] The effect according to the present invention is not limited by the contents exemplified above, and more various effects are included in the present specification. Brief description of the drawing [31] 1 is a perspective view of a conventional electrode assembly. [32] 2 is a front view of a conventional electrode assembly. [33] 3 is a schematic view of an electrode laminate according to an embodiment of the present invention. [34] 4 is a schematic view showing a state of folding the electrode stack according to an embodiment of the present invention. [35] 5 is a schematic diagram of an electrode assembly according to an embodiment of the present invention. [36] 6 is a schematic view of an electrode laminate according to another embodiment of the present invention. [37] 7 is a schematic view showing a state of folding an electrode stack according to another embodiment of the present invention. [38] 8 is a schematic diagram of an electrode assembly according to another embodiment of the present invention. Best mode for carrying out the invention [39] Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout. [40] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used with the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless clearly specifically defined. [41] The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components. [42] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. [43] 3 is a schematic diagram of an electrode stack 11 according to an embodiment of the present invention. [44] According to an embodiment of the present invention, since the first electrode 101 is formed in a single sheet shape, there is no need to be fixed to the electrode assembly 10 with a tape, so that wrinkles or swells occur in the electrode, or the active material of the electrode It is possible to prevent the electrode from being damaged such as detachment. In addition, since the first electrode 101 is a single-sided electrode, an unnecessary electrode active material is not formed in the outermost portion of the electrode assembly 10 , so that the energy density relative to the volume can be improved. In addition, since it is not necessary to manufacture the unit cell first, the continuous process is easy, thereby saving process time. [45] To this end, in the method for manufacturing the electrode assembly 10 according to an embodiment of the present invention, the separator 103 formed in a single sheet shape is disposed on one surface of the first electrode 101 formed in a single sheet shape in the same direction. laminating with; forming an electrode stack 11 by seating the second electrodes 102 formed of a plurality of pieces at regular intervals on the separator 103; and folding the electrode stack 11 by in-folding and out-folding the first electrode 101 and the separator 103 , wherein the first electrode 101 is a first electrode assembly. The entire 1011 is a single-sided electrode in which the first electrode active material 1012 is applied only on one surface, and the second electrode 102 is a second electrode current collector 1021 and the second electrode active material 1022 is applied to both surfaces. It is a coated double-sided electrode. [46] The electrode assembly 10 according to an embodiment of the present invention manufactured in this way includes a first electrode 101 formed in a single sheet shape, in which in-folding and out-folding are repeated at regular intervals; a second electrode 102 formed of a plurality of pieces, each interposed in a space formed by folding the first electrode 101; and a separator formed in a single sheet shape, interposed between the first electrode 101 and the second electrode 102, and repeated in-folding and out-folding together with the first electrode 101 at regular intervals ( 103), wherein the first electrode 101 is a single-sided electrode in which a first electrode active material 1012 is applied to only one surface of a first electrode current collector 1011, and the second electrode 102 is a It is a double-sided electrode in which the second electrode active material 1022 is applied to both surfaces of the two-electrode current collector 1021 . [47] As described above, in order to manufacture the electrode assembly 10 , a positive electrode active material slurry is applied to a positive electrode current collector, and a negative electrode active material slurry is applied to a negative electrode current collector to prepare a positive electrode and a negative electrode. The electrode assembly 10 is formed by stacking the separator 103 interposed between the positive electrode and the negative electrode. [48] The positive electrode and the negative electrode used in the present invention are not particularly limited, and the electrode active material may be prepared in the form of binding to the electrode current collector according to a conventional method known in the art. Here, the positive electrode may be manufactured by, for example, coating a slurry of a positive electrode active material, a conductive agent, and a binder on a positive electrode current collector, drying and pressing the slurry. At this time, if necessary, the slurry may further include a filler. The positive electrode may be manufactured in a sheet shape and mounted on a roll. [49] The positive electrode current collector is generally manufactured to a thickness of 3 to 500 μm. The positive electrode current collector is usually made of a material having high conductivity without causing chemical change. Such a material may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or a surface treatment of carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel, but is not limited thereto. In addition, the positive electrode current collector may form fine irregularities on the surface in order to increase the adhesion of the positive electrode active material. In addition, the positive electrode current collector may be manufactured in various forms such as a film, a sheet, a foil, a net, a porous body, a foam body, a nonwoven body, and the like. [50] In the case of a lithium secondary battery, the cathode active material may include, for example, a layered compound such as lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), or a compound substituted with one or more transition metals; Lithium manganese oxide, such as Formula Li 1 + x Mn 2 -x O 4 ( x is 0 to 0.33), LiMnO 3 , LiMn 2 O 3 , LiMnO 2 ; lithium copper oxide (Li 2 CuO 2 ); LiV 3 O 8 , LiFe 3 O 4 ,V 2 O 5 , Cu 2vanadium oxides such as V 2 O 7 ; Nickel (Ni) site-type lithium nickel oxide represented by the formula LiNi 1 - x M x O 2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 to 0.3); Formula LiMn 2 - x M x O 2 (M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or Li 2 Mn 3 MO 8 (M = Fe, Co, Ni, Cu or Zn ) represented by lithium manganese composite oxide; LiMn 2 O 4 in which a part of Li in the formula is substituted with an alkaline earth metal ion ; disulfide compounds; Fe 2 (MoO 4 ) 3 and so on. However, it is not limited only to these. [51] The conductive agent is typically added in an amount of 1 to 50% by weight based on the total weight of the mixture including the positive active material. The conductive agent is usually made of a material having conductivity without causing a chemical change. As such a material, For example, graphite, such as natural graphite and artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, furnace black, channel black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; A conductive material such as a polyphenylene derivative may be used. [52] The binder is a component that assists in bonding between the active material and the conductive agent and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material. Such binder is typically polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , polypropylene, ethylene-propylene-diene ter polymer (EPDM), sulfonated EPDM, styrene butyrene rubber, fluororubber, various copolymers, and the like. [53] The filler is optionally used as a component for suppressing the expansion of the positive electrode. And if it is a fibrous material without causing a chemical change, it can generally be used as a filler. The filler may be, for example, an olipine-based polymer such as polyethylene or polypropylene; It may be a fibrous material such as glass fiber or carbon fiber. [54] The negative electrode may be manufactured, for example, by coating the negative electrode active material on the negative electrode current collector, followed by drying and pressing. If necessary, the negative active material may optionally include a conductive agent, a binder, a filler, and the like. The negative electrode may be manufactured in a sheet shape and mounted on a roll. [55] The negative electrode current collector is generally manufactured to a thickness of 3 to 500 μm. The negative electrode current collector is usually made of a material having conductivity without causing chemical change. Copper, stainless steel, aluminum, nickel, titanium, calcined carbon, which are the most representative of such materials, those in which carbon, nickel, titanium, silver, etc. are surface-treated on the surface of copper or stainless steel, or aluminum-cadmium alloy, etc. to be. In addition, the negative electrode current collector may form fine irregularities on the surface to increase the bonding strength of the negative electrode active material. In addition, the negative electrode current collector may be manufactured in various forms such as a film, a sheet, a foil, a net, a porous body, a foam body, a nonwoven body, and the like. [56] The negative electrode active material includes, for example, carbon such as non-graphitizable carbon and graphitic carbon; Li x Fe 2 O 3 (0≤x≤1), LixWO 2 (0≤x≤1), Sn x Me 1 -xMe'yOz (Me: Mn, Fe, Pb, Ge; Me': Al, B, metal complex oxides such as P, Si, elements of Groups 1, 2, and 3 of the periodic table, halogen;0