Cross Citation with Related Applications [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0049375 dated April 27, 2018, 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 a separator for a lithium secondary battery and a lithium secondary battery including the same, and more particularly, to a separator for a lithium secondary battery including a gel polymer electrolyte and a lithium secondary battery using the same. background [5] 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, lithium secondary batteries exhibiting high energy density and operating potential, long cycle life, and low self-discharge rate. Batteries have been commercialized and widely used. [6] In addition, as interest in environmental issues has increased in recent years, electric vehicles (EVs) and hybrid electric vehicles (HEVs) that can replace vehicles using fossil fuels such as gasoline vehicles and diesel vehicles, which are one of the main causes of air pollution, have been developed. A lot of research is going on. [7] Such electric vehicles (EVs), hybrid electric vehicles (HEVs), etc. use a nickel-metal hydride (Ni-MH) secondary battery or a lithium secondary battery with high energy density, high discharge voltage and output stability as a power source. When used in electric vehicles, it must be able to be used for more than 10 years under harsh conditions as well as high energy density and high output in a short time. characteristics are inevitably required. [8] In general, lithium secondary batteries are manufactured using an anode and a cathode, a separator interposed therebetween, and an electrolyte that is a lithium ion transfer medium. Conventional secondary batteries are liquid electrolytes, especially An ion conductive organic liquid electrolyte in which a salt is dissolved in a non-aqueous organic solvent has been mainly used. [9] However, when a liquid electrolyte is used as described above, there is a high possibility that the electrode material is degraded and the organic solvent is volatilized, and there is a problem in safety such as combustion due to an increase in ambient temperature and the temperature of the battery itself. In particular, a lithium secondary battery has a problem in that a gas is generated inside the battery due to decomposition of the carbonate organic solvent and/or a side reaction between the organic solvent and the electrode during charging and discharging, thereby expanding the battery thickness. Accordingly, the performance and safety of the battery are inevitably deteriorated. [10] In general, it is known that the safety of the battery is improved in the order of liquid electrolyte < gel polymer electrolyte < solid polymer electrolyte, but on the other hand, battery performance decreases. Currently, it is known that the solid polymer electrolyte has not yet been commercialized due to poor battery performance. [11] On the other hand, in the case of a gel polymer electrolyte, it is possible to maintain a constant thickness of the battery due to excellent electrochemical safety, and to produce a thin film battery due to excellent contact between the electrode and the electrolyte due to the inherent adhesion of the gel, Recently, gel polymer electrolytes have been widely used. [12] On the other hand, the separator is an inactive material that does not participate in the electrochemical reaction or provides a path for lithium ions to move in order to operate the battery. It is one of the key materials to influence. [13] In the case of a lithium secondary battery, heat may be easily generated due to kinetic energy generated during repeated charging and discharging, and the separator is vulnerable to this heat. In particular, in the case of a separator using polyethylene (PE), a 'shut down' phenomenon may occur that starts to melt (melt) near about 130°C and closes the pores, and at 150°C or higher, it completely melts and an internal short circuit may fail to prevent it and cause it to collapse (meltdown or destroy mechanical integrity). [14] In order to overcome this problem, recently, studies to enhance durability, such as using a dip coating method of coating the surface of the separator with inorganic particles and a polymer binder, are continuing. [15] However, when the gel polymer electrolyte and a separator having a coating layer including inorganic particles are used together, there is no component capable of imparting adhesion between the coating layer and the electrolyte. Therefore, the electrolyte is not uniformly formed on the separator, which increases the interfacial resistance, and there is a problem in that a short circuit in the battery occurs. [16] Therefore, a separator capable of improving the safety and lifespan characteristics of a battery by improving the adhesion between the gel polymer electrolytes, while maintaining excellent processability and maintaining a certain level of durability or more, and lithium containing the same to be applied to various battery types There is a need for the development of secondary batteries. [17] (Patent Document 1) Korean Patent Publication No. 10-2015-0131513 DETAILED DESCRIPTION OF THE INVENTION technical challenge [18] An object of the present invention is to provide a separator for a lithium secondary battery in which safety and lifespan characteristics of a battery are improved by increasing adhesion with a gel polymer electrolyte, and processability can also be improved by having a multilayer structure, and a lithium secondary battery including the same. means of solving the problem [19] In one aspect, the present invention provides a substrate; a first coating layer comprising a first organic binder capable of being combined with a gel polymer electrolyte through an epoxy ring-opening reaction; and a second coating layer comprising a second organic binder, wherein the first organic binder includes a functional group capable of a ring-opening reaction with an epoxy group or a combination thereof, and the gel polymer electrolyte is an epoxy group, an epoxy group and a ring-opening reaction capable of It provides a separator for a lithium secondary battery that is formed by polymerization of an oligomer containing a functional group or a combination thereof. [20] In this case, the functional group capable of a ring-opening reaction with the epoxy group is at least one functional group selected from the group consisting of a hydroxyl group (OH), a carboxylic acid group (COOH), an amine group, an isocyanate group, a mercaptan group, and an imide group. [21] On the other hand, the first organic binder is an alkylene group having 1 to 5 carbon atoms in which at least one halogen element is substituted, an alkylene oxide group having 1 to 5 carbon atoms, and an alkylene oxide having 1 to 5 carbon atoms in which at least one halogen element is substituted. A group comprising a unit comprising at least one selected from the group consisting of a group, an imide group and a celluloid, and an epoxy group, a functional group capable of a ring-opening reaction with an epoxy group, or a combination thereof may be substituted in the main chain consisting of the unit. [22] On the other hand, the oligomer includes at least one unit selected from the group consisting of a unit containing an alkylene oxide group and a unit containing an amine group, [23] An epoxy group and a functional group capable of a ring-opening reaction with the epoxy group or a combination thereof may be substituted in the main chain of the unit. [24] In one embodiment of the present invention, at least one coating layer selected from the first coating layer and the second coating layer is Si, Al, Ti, Zr, Sn, Ce, Mg, Ca, Zn, Y, Pb, Ba, Hf , and may include an inorganic oxide including at least one element selected from the group consisting of Sr. [25] In another embodiment of the present invention, the first coating layer may be formed on the substrate, the second coating layer may be formed on the first coating layer, and in another embodiment, the second coating layer is the It is formed on a substrate, and the first coating layer may be formed on the second coating layer. [26] As an embodiment of the present invention, an electrode assembly comprising at least one unit cell including at least one positive electrode, at least one negative electrode, and at least one first separator interposed between the positive electrode and the negative electrode; and a gel polymer electrolyte formed by polymerization of an oligomer containing an epoxy group, an epoxy group, a functional group capable of a ring-opening reaction, or a combination thereof; and the first separator is a lithium secondary battery, which is a separator for the lithium secondary battery. to provide. Effects of the Invention [27] The separator for a lithium secondary battery according to the present invention is provided with a first coating layer including a first organic binder capable of being combined with a gel polymer electrolyte through an epoxy ring-opening reaction, thereby improving bonding strength with the gel polymer electrolyte, thereby preventing a short circuit inside the battery to improve safety and improve the lifespan characteristics of a lithium secondary battery. Brief description of the drawing [28] 1 shows a cross-section of a separator according to Examples 1 and 2 of the present invention. [29] 2 shows a cross-section of a separator according to Examples 3 and 4 of the present invention. Best mode for carrying out the invention [30] Hereinafter, the present invention will be described in more detail. [31] The terms or words used in the present specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention. [32] The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. [33] In this specification, terms such as "comprises", "comprises" or "have" are intended to designate the presence of an embodied feature, number, step, element, or a combination thereof, but one or more other features or It should be understood that the existence or addition of numbers, steps, elements, or combinations thereof is not precluded in advance. [34] Meanwhile, in the present invention, unless otherwise specified, "*" means a connected portion between the same or different atoms or terminal ends of chemical formulas. [35] In addition, in the present invention, the weight average molecular weight (Mw) can be measured using gel permeation chromatography (Gel Permeation Chromatography: GPC). For example, after preparing a sample sample of a certain concentration, the GPC measurement system alliance 4 device is stabilized. When the instrument is stabilized, a standard sample and a sample sample are injected into the instrument to obtain a chromatogram, and then the molecular weight can be calculated according to the analysis method (System: Alliance 4, Column: Ultrahydrogel linear Х 2, eluent: 0.1M NaNO 3 ( pH 7.0 phosphate buffer, flow rate: 0.1 mL/min, temp: 40°C, injection: 100 μl). [36] [37] [38] The separator for a lithium secondary battery according to the present invention comprises (1) a substrate, (2) a first coating layer comprising a first organic binder capable of being combined with a gel polymer electrolyte through an epoxy ring-opening reaction, and (3) a second organic binder. a second coating layer comprising a, wherein the first organic binder includes a functional group capable of a ring-opening reaction with an epoxy group or a combination thereof, and the gel polymer electrolyte includes an epoxy group, a functional group capable of a ring-opening reaction with an epoxy group, or a combination thereof oligomers are formed by polymerization. [39] [40] As the substrate, a porous substrate may be used, and in general, the porous substrate may be used without any particular limitation as long as it can be used as a separator material for an electrochemical device. Examples of the porous substrate include polyolefin, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenyl There is a nonwoven fabric or a porous polymer film formed of at least any one of polymer resins such as lensulfide and polyethylene naphthalene, or a laminate of two or more thereof, but is not particularly limited thereto. [41] [42] The first coating layer includes a gel polymer electrolyte and a first organic binder that can be combined through an epoxy ring-opening reaction. In addition, the first coating layer may optionally further include an inorganic oxide. [43] In this case, the first organic binder includes an epoxy group and a functional group capable of a ring-opening reaction or a combination thereof, and the gel polymer electrolyte is formed by polymerizing an oligomer containing an epoxy group, an epoxy group, a ring-opening reaction capable functional group, or a combination thereof. . In this case, the first coating layer may optionally further include an inorganic oxide. [44] Specifically, the functional group capable of a ring-opening reaction with the epoxy group may be at least one functional group selected from the group consisting of a hydroxyl group (OH), a carboxylic acid group (COOH), an amine group, an isocyanate group, a mercaptan group, and an imide group. [45] More specifically, the amine group may be represented by -NR 1 R 2 , wherein R 1 and R 2 are each independently hydrogen (H), a substituted or unsubstituted chain alkyl group having 1 to 10 carbon atoms, and 1 to carbon atoms. It may be at least one selected from the group consisting of a substituted or unsubstituted cyclic alkyl group of 10. [46] More specifically, the imide group may be represented by -R 3 -CO-N(R 4 )-CO-R 5 , wherein R 3 to R 5 are each independently hydrogen (H), substituted with 1 to 10 carbon atoms. Or it may be at least one selected from the group consisting of an unsubstituted chain alkyl group and a substituted or unsubstituted cyclic alkyl group having 1 to 10 carbon atoms. [47] Meanwhile, the first organic binder is a copolymer of general organic binders well known in the art, for example, PVdF (Poly (Vinylidene fluoride)), PVdF-co-HFP (Poly (Vinylidene fluoride) and hexafluoropropylene)) Binders in which an epoxy group and/or a functional group capable of ring-opening reaction with an epoxy group are substituted may be used. More specifically, the first organic binder may include, in addition to the functional group, an alkylene group having 1 to 5 carbon atoms, an alkylene oxide group having 1 to 5 carbon atoms, in which at least one halogen element (F, Cl, Br, I) is substituted, It may further include a unit comprising at least one selected from the group consisting of digi, celluloid. [48] In this case, an epoxy group, a functional group capable of a ring-opening reaction with an epoxy group, or a combination thereof may be substituted in the main chain made of the unit. Specifically, hydrogen (H) positioned in the main chain may be substituted with an epoxy group, a functional group capable of ring-opening reaction with an epoxy group, or a combination thereof, and the degree of substitution may be calculated in mole %. However, the number or position of the functional groups to be attached is not specified. [49] For example, the unit including an alkylene group in which at least one halogen element is substituted may be represented by at least one selected from units represented by Formula X-1 or X-2 below. [50] [Formula X-1] [51] [52] In Formula X-1, m1 is an integer of 1 to 10,000, preferably an integer of 1 to 7,500, and more preferably an integer of 1 to 5,000. [53] [Formula X-2] [54] [55] In Formula X-2, m2 and m3 are each independently an integer of 1 to 10,000, preferably an integer of 1 to 7,500, and more preferably an integer of 1 to 5,000. [56] For example, a unit including an alkylene oxide group may be represented by the following Chemical Formula X-3. [57] [Formula X-3] [58] [59] In Formula X-3, m4 is an integer of 1 to 10,000, preferably an integer of 1 to 7,500, and more preferably an integer of 1 to 5,000. [60] For example, the unit including the alkylene oxide group substituted with the halogen element may be represented by the following Chemical Formula X-4. [61] [Formula X-4] [62] [63] In Formula X-4, m5 is an integer of 1 to 10,000, preferably an integer of 1 to 7,500, and more preferably an integer of 1 to 5,000. [64] For example, the unit including the imide group may be represented by the following Chemical Formula X-5. [65] [Formula X-5] [66] [67] In Formula X-5, m6 is an integer of 1 to 10,000, preferably an integer of 1 to 7,500, and more preferably an integer of 1 to 5,000. [68] For example, the unit including the celluloid may be represented by the following Chemical Formula X-6. [69] [Formula X-6] [70] [71] In Formula X-6, m7 is an integer of 1 to 10,000, preferably an integer of 1 to 7,500, and more preferably an integer of 1 to 5,000. [72] On the other hand, the first organic binder may be included in an amount of 100% by weight based on the total weight of the first coating layer to form a coating layer alone, and when an inorganic oxide is further included, 10 based on the total weight of the first coating layer It may be included in an amount of from 10 wt% to 80 wt%, specifically 10 wt% to 60 wt%, and more specifically 10 wt% to 50 wt%. [73] The inorganic oxide is a compound having good heat resistance and durability, and when coated on a separator, it is possible to improve the mechanical strength of the separator as well as improve heat resistance. [74] Specifically, for example, the inorganic oxide comprises at least one element selected from the group consisting of Si, Al, Ti, Zr, Sn, Ce, Mg, Ca, Zn, Y, Pb, Ba, Hf, and Sr. It may include, and preferably, may include at least one element selected from the group consisting of Si, Al, Ti and Zr. [75] More specifically, the inorganic oxide is SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , SnO 2 , CeO 2 , MgO, CaO, ZnO, Y 2 O 3 , 　Pb(Zr,Ti)O 3　(PZT) , Pb (1-a1) La a1 Zr (1-b1) Ti b1 O 3　(0≤a1≤1, 0≤b1≤1, PLZT), PB(Mg 3 Nb 2/3 )O 3 -PbTiO 3　 ( PMN-PT), BaTiO 3, HfO 2 (hafnia), SrTiO 3　 and the like, and the inorganic oxides listed above generally have properties that do not change their physical properties even at a high temperature of 200° C. or higher. More preferably, the inorganic oxide may include at least one selected from the group consisting of SiO 2 , Al 2 O 3 , TiO 2 and ZrO 2 . [76] The inorganic oxide may be included in an amount of 20 wt% to 90 wt%, specifically 40 wt% to 90 wt%, and more specifically, 50 wt% to 90 wt% based on the total weight of the first coating layer. % may be included. When the inorganic oxide is included within the above range, it is possible to prevent the inorganic oxide from being detached from the first coating layer and to improve durability of the separator. [77] The second coating layer includes a second organic binder, and may optionally further include an inorganic oxide. [78] The second organic binder is used to improve processability, and optionally to fix the inorganic oxide when it further includes an inorganic oxide. Specifically, the second organic binder is a copolymer of general organic binders well known in the art, for example, PVdF (Poly (Vinylidene fluoride)), PVdF-co-HFP (Poly (Vinylidene fluoride) and hexafluoropropylene) ) can be used. On the other hand, in the case of the second organic binder, 100% by weight of the second coating layer based on the total weight of the second coating layer may be included to form a coating layer alone, and when an inorganic oxide is further included, the second It may be included in an amount of 10 wt% to 80 wt%, specifically 10 wt% to 70 wt%, and more specifically 10 wt% to 60 wt%, based on the total weight of the coating layer. [79] The inorganic oxide is a compound having good heat resistance and durability, and when coated on a separator, it is possible to improve the mechanical strength of the separator as well as improve heat resistance. [80] Specifically, for example, the inorganic oxide comprises at least one element selected from the group consisting of Si, Al, Ti, Zr, Sn, Ce, Mg, Ca, Zn, Y, Pb, Ba, Hf, and Sr. It may include, and preferably, may include at least one element selected from the group consisting of Si, Al, Ti and Zr. [81] More specifically, the inorganic oxide is SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , SnO 2 , CeO 2 , MgO, CaO, ZnO, Y 2 O 3 , 　Pb(Zr, Ti)O 3　(PZT) , Pb (1-a1) La a1 Zr (1-b1) Ti b1 O 3　(0≤a1≤1, 0≤b1≤1, PLZT), PB(Mg 3 Nb 2/3 )O 3 -PbTiO 3　 ( PMN-PT), BaTiO 3, HfO 2 (hafnia), SrTiO 3　 and the like, and the inorganic oxides listed above generally have properties that do not change their physical properties even at a high temperature of 200° C. or higher. More preferably, the inorganic oxide may include at least one selected from the group consisting of SiO 2 , Al 2 O 3 , TiO 2 and ZrO 2 . The inorganic oxide may be included in an amount of 20 wt% to 90 wt%, specifically 40 wt% to 90 wt%, and more specifically, 50 wt% to 90 wt% based on the total weight of the second coating layer. % may be included. When the inorganic oxide is included within the above range, it is possible to prevent the inorganic oxide from being desorbed from the second coating layer, and it is possible to improve the durability of the separator. [82] [83] On the other hand, in the case of the separator for a lithium secondary battery according to the present invention, (1) a structure in which a first coating layer is formed on a substrate, and a second coating layer is formed on the first coating layer, or (2) a second coating layer is formed on the substrate and the first coating layer may be formed in a structure formed on the second coating layer. [84] [85] At this time, when the first coating layer is first formed on the substrate as in the structure (1), a second coating layer containing an inorganic oxide having strong durability and heat resistance is formed on the first coating layer, so that the separator formed in this way is provided. A lamination-stack process or a lamination-folding process using the electrode assembly may also be easily performed. Specifically, in the case of a lamination-stack type lithium secondary battery, a unit cell including a positive electrode/separator/negative electrode is formed through a lamination process of first adhering one or more positive or negative electrodes and one or more separators, and then the unit It can be manufactured by stacking/welding cells with a separator interposed therebetween to form an electrode assembly, inserting the electrode assembly into a battery case, and then injecting electrolyte. On the other hand, in the case of a lamination-folding lithium secondary battery, the unit cells manufactured through the lamination process are folded using a long-length separator sheet to form an electrode assembly, and the electrode assembly is inserted into the battery case and then the electrolyte It can be prepared by injecting On the other hand, in the case of the second coating layer, since the coating layer is formed of the inorganic oxide and the second organic binder and voids exist inside the coating layer, the oligomer contained in the electrolyte composition penetrates and polymerizes even within the gap between the first coating layer and the gel polymer electrolyte. , the bonding force between the gel polymer electrolyte and the separator is maintained at a certain level or higher. [86] On the other hand, when the second coating layer is first formed on the substrate as in the structure (2), the mechanical properties of the substrate can be improved by preferentially coating the substrate with a durable inorganic oxide, and the economic feasibility of the process for making the separator is improved. can be improved However, when designing the separator, it is not limited to one of the two stacked structures, and the stacked structure may be set differently depending on the purpose of use and the manufacturing process of the separator for a lithium secondary battery. In addition, it is also possible to further form a multi-layered coating layer by further laminating the first coating layer and/or the second coating layer in order to further improve the heat resistance or mechanical performance of the separator in the laminate structure. [87] Meanwhile, the total thickness of the sum of the thickness of the first coating layer and the thickness of the second coating layer may be 0.2 μm to 20 μm. Specifically, the total thickness may be 0.5 μm to 17 μm, and more specifically, the total thickness may be 1 μm to 15 μm. When the total thickness is within the above range, the mechanical performance of the separator and binding force with the gel polymer electrolyte may be improved without degrading the mobility of lithium ions. [88] [89] [90] Hereinafter, a lithium secondary battery is demonstrated. [91] A lithium secondary battery according to the present invention includes: (1) an electrode assembly comprising at least one unit cell including at least one positive electrode, at least one negative electrode, and at least one first separator interposed between the positive electrode and the negative electrode; And (2) a lithium secondary battery comprising a gel polymer electrolyte formed by polymerization of an oligomer containing an epoxy group, an epoxy group, a functional group capable of a ring-opening reaction, or a combination thereof, [92] The first separator may be a separator according to the present invention. [93] At this time, since the separation membrane according to the present invention is the same as the above-described content, a detailed description thereof will be omitted. Hereinafter, each configuration of the unit cell included in the electrode assembly will be described. [94] [95] First, at least one positive electrode included in the unit cell may be prepared by coating a positive electrode mixture slurry including a positive electrode active material, an electrode binder, an electrode conductive material and a solvent on a positive electrode current collector. [96] 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, etc. may be used. [97] The positive active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium composite metal oxide including lithium and one or more metals such as cobalt, manganese, nickel or aluminum. have. More specifically, the lithium composite metal oxide is a lithium-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4 , etc.), a lithium-cobalt-based oxide (eg, LiCoO 2 , etc.), lithium-nickel-based oxide (eg, LiNiO 2 , etc.), lithium-nickel-manganese oxide (eg, LiNi 1-Y1 Mn Y1 O 2 (here, 0