Title of Invention: Separator for electrochemical device including heat-resistant layer and secondary battery including same technical field [One] This application claims priority based on Korean Patent Application No. 10-2019-0100503 filed on August 16, 2019. The present invention relates to a separator for an electrochemical device having improved thermal stability. The electrochemical device may be a primary battery or a secondary battery, and the secondary battery includes a lithium ion secondary battery. [2] background [3] Recently, interest in energy storage technology is increasing. Efforts for research and development of electrochemical devices are becoming more concrete as the fields of application are expanding to cell phones, camcorders, notebook PCs, and even the energy of electric vehicles. Electrochemical devices are receiving the most attention in this aspect, and among them, the development of rechargeable batteries that can be charged and discharged is the focus of interest. and research and development of battery design. [4] Among the currently applied secondary batteries, lithium secondary batteries developed in the early 1990s have a higher operating voltage and significantly higher energy density than conventional batteries such as Ni-MH, Ni-Cd, and lead sulfate batteries that use aqueous electrolyte solutions. is in the spotlight as However, these lithium ion batteries have safety problems such as ignition and explosion due to the use of an organic electrolyte, and are difficult to manufacture. Recent lithium ion polymer batteries have improved the weaknesses of lithium ion batteries and are considered one of the next-generation batteries. This is urgently required. [5] Electrochemical devices as described above are produced by many companies, but their safety characteristics show different aspects. It is very important to evaluate the safety and secure the safety of these electrochemical devices. The most important consideration is that the electrochemical device must not cause injury to the user when malfunctioning, and for this purpose, the safety standards strictly regulate ignition and fuming within the electrochemical device. In terms of safety characteristics of the electrochemical device, there is a high risk of causing an explosion when the electrochemical device is overheated and thermal runaway occurs or the separator is penetrated. In particular, polyolefin-based porous substrates commonly used as separators for electrochemical devices exhibit extreme thermal contraction behavior at a temperature of 100 degrees Celsius or higher due to material properties and characteristics of the manufacturing process including stretching, so that between the anode and the cathode There is a problem causing a short circuit. [6] In order to solve the safety problem of the electrochemical device, a separator in which a porous composite coating layer is formed by coating a mixture containing inorganic particles and a polymer binder on at least one surface of a porous separator sheet (substrate) has been proposed. Since the inorganic particles included in the coating layer have high heat resistance compared to the polymer material, there is an effect of preventing a short circuit between the anode and the cathode even when the electrochemical device is overheated compared to the case of using a substrate made of only a polymer material. However, the interfacial resistance between the electrode and the separator tends to decrease due to the formation of such a composite coating layer, and the inorganic particles are oxidized according to repeated charging and discharging, so there is a problem in that the oxidation stability of the electrolyte is low. [7] [8] DETAILED DESCRIPTION OF THE INVENTION technical challenge [9] An object of the present invention is to provide a separator including a heat-resistant coating layer and an electrochemical device including the same. Furthermore, it is another object of the present invention to provide a separator in which oxidation stability of inorganic particles included in the heat-resistant coating layer is improved and an interface resistance between the separator and an electrode is reduced, and an electrochemical device including the same. It will be readily apparent that other objects and advantages of the present invention may be realized by means or methods and combinations thereof recited in the claims. [10] means of solving the problem [11] A first aspect of the present invention relates to the separation membrane, comprising a porous polymer substrate and a heat-resistant coating layer disposed on at least one surface of the porous polymer substrate, wherein the heat-resistant coating layer includes heat-resistant particles and the heat-resistant particles are particulate inorganic materials Fluorine (F) atoms are introduced into the surface of the material. [12] A second aspect of the present invention is that according to the first aspect, the inorganic material is stable to oxidation and/or reduction reactions in the operating voltage range of electrochemical irradiation. [13] A third aspect of the present invention is the first or second aspect, wherein the heat-resistant particles are alumina (Al 2 O 3 ), aluminum hydroxide (Al(OH) 3 ) and boehmite having fluorine (F) atoms introduced to the surface. (AlOOH), B(OH) 3 or at least one of them, and is in the form of a particle. [14] In a fourth aspect of the present invention, in at least one of the first to third aspects, the heat-resistant particles are alumina (Al 2 O 3 ), aluminum hydroxide (Al(OH) 3 ) into which fluorine (F) atoms are introduced on the surface. ) and boehmite (AlOOH), or at least one of them, and is in a particulate form, and the fluorine (F) atom is introduced in the form of AlF 3 . [15] In a fifth aspect of the present invention, in at least one of the first to fourth aspects, the heat-resistant particles include aluminum hydroxide (Al(OH) 3 ) having a fluorine (F) atom introduced thereto, and are particulate. [16] A sixth aspect of the present invention is that in at least one of the first to fifth aspects, the heat-resistant particles have a component ratio of fluorine (F) atoms on the particle surface of 5 atomic% or more. [17] A seventh aspect of the present invention is the method according to at least one of the first to sixth aspects, wherein the heat-resistant particles are mixed with an aqueous hydrogen fluoride (HF) aqueous solution and an inorganic material and heat-treating the fluorine atoms introduced to the surface of the particles. will be. [18] In an eighth aspect of the present invention, in at least one of the first to seventh aspects, the heat-resistant particles are included in 50% by weight or more of 100% by weight of inorganic particles included in the heat-resistant coating layer. [19] In a ninth aspect of the present invention, in at least one of the first to eighth aspects, the heat-resistant particles have a particle diameter of 0.01 μm to 2.0 μm. [20] In a tenth aspect of the present invention, in at least one of the first to ninth aspects, the separator has a filling density of the heat-resistant coating layer of 0.8 g/cm 3 or more, and the thickness of the heat-resistant coating layer of the separator is less than 10 μm. Resistance is less than 1 ohm. [21] An eleventh aspect of the present invention relates to an electrochemical device, wherein the electrochemical device includes a cathode, an anode, a separator and an electrolyte interposed between the cathode and the anode, the separator comprising at least one of the first to ninth aspects According to any one, wherein the electrolyte is a lithium salt LiPF 6 , LiBF 4 , LiAsF 6 , LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiC(CF 2 SO 2 ) 3 Or at least one of them to include a mixture that [22] Effects of the Invention [23] The separator according to the present invention and an electrochemical device including the same have low internal resistance between the separator and the electrode. The separator includes heat-resistant particles in the heat-resistant coating layer, and the heat-resistant particles are doped with fluorine (F) on the surface of inorganic particles. This has the effect of improving the heat resistance characteristics of the separation membrane. In addition, the decomposition reaction of the lithium salt used as an electrolyte component is suppressed by the fluorine atom introduced into the heat-resistant particles, and thus ionic conductivity and resistance characteristics are improved. In addition, the separator into which the heat-resistant particles are introduced has excellent resistance properties and has a high oxidation stability to the electrolyte, thereby improving the electrochemical stability of the battery. [24] Brief description of the drawing [25] The drawings accompanying the present specification illustrate preferred embodiments of the present invention, and serve to better understand the technical spirit of the present invention together with the above-described content of the present invention, so the present invention is limited only to the matters described in such drawings is not interpreted as On the other hand, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated in order to emphasize a clearer description. [26] 1 shows the surface shape and EDX (Energy Dispersive X-ray Spectroscopy) component analysis area of ​​the fluorine-doped aluminum hydroxide obtained in Preparation Example 1. [27] Figure 2 shows the surface shape of the aluminum hydroxide not doped with fluorine and EDX (Energy Dispersive X-ray Spectroscopy) component analysis area. [28] 3 shows a mapping graph obtained as a result of EDX analysis of the aluminum hydroxide obtained by the fluorine particle introduction treatment of Preparation Example 1. FIG. [29] 4 shows a mapping graph obtained as a result of EDX analysis of aluminum hydroxide before the introduction of fluorine particles in Preparation Example 1. FIG. [30] Modes for carrying out the invention [31] 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 appropriately defines 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 done. Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all the technical spirit of the present invention, so they can be substituted at the time of the present application It should be understood that various equivalents and modifications may exist. [32] [33] Throughout this specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated. [34] [35] In addition, the terms "about", "substantially", etc. used throughout this specification are used as meanings at or close to the numerical values ​​when manufacturing and material tolerances inherent in the stated meaning are presented to help the understanding of the present application It is used to prevent an unconscionable infringer from using the mentioned disclosure in an unreasonable way. [36] [37] Throughout this specification, the description of “A and/or B” means “A or B or both”. [38] [39] Certain terminology used in the detailed description that follows is for convenience and not limitation. The words 'right', 'left', 'top' and 'bottom' indicate directions in the drawings to which reference is made. The words 'inwardly' and 'outwardly' refer respectively to directions towards or away from the geometric center of the designated device, system, and members thereof. 'Anterior', 'rear', 'above', 'below' and related words and phrases indicate positions and orientations in the drawings to which reference is made and should not be limiting. These terms include the words listed above, derivatives thereof, and words of similar meaning. [40] [41] The present invention relates to a separator for an electrochemical device and an electrochemical device including the same. In the present invention, the electrochemical device is a device that converts chemical energy into electrical energy by an electrochemical reaction, and is a concept including a primary battery and a secondary battery, and the secondary battery is capable of charging and discharging. , a lithium ion battery, a nickel-cadmium battery, a nickel-hydrogen battery, and the like. [42] [43] The separator according to the present invention includes a heat-resistant coating layer including heat-resistant particles. The heat-resistant particles are fluorine atoms (F) introduced to the surface of the inorganic material in the form of particles, which is advantageous in improving the heat-resistant stability of the separation membrane. [44] [45] Next, the separation membrane of the present invention will be described in more detail. [46] [47] 1. Separator [48] (Structure of Separator) The separator according to the present invention includes a porous substrate including a plurality of pores and a heat-resistant coating layer formed on at least one surface of the porous substrate. [49] In one embodiment of the present invention, the separator may have a thickness of 5 μm to 20 μm, and may be appropriately adjusted within the above range. For example, it may be 18 μm or less or 15 μm or less. In addition, the separation membrane will have a porosity in the range of about 38 vol% to 60 vol%. The 'porosity' means the ratio of the volume occupied by the pores to the volume of the separator, and vol% is used as its unit, and can be used interchangeably with terms such as porosity and porosity. In general, in the separator of a secondary battery, the pores should be of a size sufficient to prevent internal short circuit. [50] [51] 1) Porous substrate [52] The porous substrate refers to a substrate having a plurality of pores formed therein as an ion-conducting barrier that passes ions while blocking electrical contact between the negative electrode and the positive electrode. The pores have a structure connected to each other so that gas or liquid can pass from one side of the substrate to the other side. [53] As the material constituting such a porous substrate, either an organic material having electrical insulation or an inorganic material can be used. In particular, from the viewpoint of imparting a shutdown function to the substrate, it is preferable to use a thermoplastic resin as a constituent material of the substrate. Here, the shutdown function refers to a function of preventing thermal runaway of the battery by blocking the movement of ions by dissolving the thermoplastic resin and closing the pores of the porous substrate when the battery temperature is high. As the thermoplastic resin, a thermoplastic resin having a melting point of less than 200°C is suitable, and polyolefin is particularly preferable. [54] In addition, polymer resins such as polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, and polyethylene naphthalene It may further include at least any one of. The porous substrate may be a nonwoven fabric, a porous polymer film, or a laminate of two or more thereof, but is not particularly limited thereto. [55] [56] Specifically, the porous polymer substrate is any one of the following a) to e). [57] [58] a) a porous film formed by melting/extruding a polymer resin; [59] b) a multilayer film in which two or more layers of the porous film of a) are laminated; [60] c) a nonwoven web prepared by integrating filaments obtained by melting/spinning a polymer resin; [61] d) a multilayer film in which two or more layers of the nonwoven web of b) are laminated; [62] e) A porous composite membrane having a multilayer structure comprising at least two of a) to d). [63] [64] In the present invention, the porous substrate preferably has a thickness of 3 μm to 12 μm or 5 μm to 20 μm. If the thickness thereof is less than the above value, the function of the conductive barrier is not sufficient. On the other hand, if the thickness is excessively exceeded (ie, too thick), the resistance of the separator may excessively increase. [65] In one embodiment of the present invention, the polyolefin preferably has a weight average molecular weight of 100,000 to 5,000,000. When the weight average molecular weight is smaller than 100,000, it may become difficult to ensure sufficient mechanical properties. Moreover, when it becomes larger than 5 million, the shutdown characteristic may worsen, or shaping|molding may become difficult. In addition, the puncture strength of the porous substrate may be 300 gf or more from the viewpoint of improving the manufacturing yield. The piercing strength of a porous substrate refers to the maximum piercing load (gf) measured by performing a piercing test under the conditions of a radius of curvature of the needle tip of 0.5 mm and a piercing speed of 2 mm/sec using a Kato tech KES-G5 handy compression tester. [66] In a specific embodiment of the present invention, the porous polymer substrate can be used as long as it is a planar porous polymer substrate used in electrochemical devices, for example, has high ion permeability and mechanical strength, and the pore diameter is generally 10 nm to An insulating thin film having a thickness of 100 nm and generally 5 μm to 20 μm may be used. [67] [68] 2) Heat-resistant coating layer [69] In the present invention, the separator includes a heat-resistant coating layer formed on one surface of the porous substrate, and the heat-resistant coating layer includes heat-resistant particles. In the present invention, the heat-resistant particles have fluorine (F) introduced into the surface of the particulate inorganic material. In one embodiment of the present invention, when the amount of fluorine (F) introduced into the heat-resistant particles is too small, the desired effect will be insignificant. % or more can be controlled. In addition, in one embodiment of the present invention, the amount of fluorine (F) atoms introduced to the surface of the heat-resistant particles can be measured using an elemental analyzer such as energy dispersive X-ray spectroscopy. [70] [71] In a specific embodiment of the present invention, the inorganic material that can be used as the heat-resistant particle is not particularly limited as long as it is electrochemically stable. For example, in the operating voltage range of the electrochemical device to which the separator of the present invention is applied (eg, 0 to 5V based on Li/Li+), it is stable to oxidation and/or reduction reactions, that is, oxidation/reduction reactions do not occur. If it is, it is not particularly limited. [72] [73] In one embodiment of the present invention, the inorganic material includes BaTiO 3 , Pb(Zr,Ti)O 3 (PZT), b 1-x La x Zr 1-y Ti y O 3 (PLZT, 0