Specification Title of Invention: Separator for electrochemical device and electrochemical device comprising same technical field [One] This application claims priority based on Korean Patent Application No. 10-2019-0148978 filed on November 19, 2019. The present invention relates to a separator for an electrochemical device and an electrochemical device including the same, to a separator having a thin thickness, excellent adhesion, and improved dielectric breakdown performance, and to an electrochemical device including the same. [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 battery design research and development. [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 gaining popularity as However, such lithium ion batteries have safety problems such as ignition and explosion due to the use of an organic electrolyte, and are difficult to manufacture. [5] 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. [6] Although the above electrochemical devices are produced by many companies, 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 when an electrochemical device malfunctions, it must not cause injury to the user. For this purpose, the safety standards strictly regulate ignition and fuming within the electrochemical device. In the safety characteristics of the electrochemical device, when the electrochemical device is overheated and thermal runaway occurs or the separator is penetrated, there is a high risk of causing an explosion. In particular, polyolefin-based porous substrates commonly used as separators for electrochemical devices exhibit extreme thermal shrinkage behavior at a temperature of 100° C. or higher due to material properties and characteristics of the manufacturing process including elongation, resulting in a short circuit between the cathode and the anode. caused [7] In order to solve the safety problem of the electrochemical device, a separator in which a porous inorganic 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 inorganic coating layer have higher heat resistance than 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, as shown in FIG. 1 , the inorganic particles introduced into the coating layer were not uniformly dispersed in the slurry during the preparation of the slurry for forming the inorganic coating layer, so there was a problem that localized localization or aggregation of the particles occurred, which inhibits the thinning of the separator and prevents the separation of the separator. This resulted in the occurrence of a hi-pot defect rate. Accordingly, there is a growing demand for the development of a separator with excellent dielectric breakdown performance while reducing the occurrence of agglomeration of secondary particles in the inorganic coating layer along with the thinning of the separator. [8] DETAILED DESCRIPTION OF THE INVENTION technical challenge [9] An object of the present invention is to provide a separator for an electrochemical device with a low content of secondary particles, which are aggregates of inorganic particles in an inorganic coating layer, and a high breakdown voltage, so that the high-pot defect rate is low. Another object of the present invention is to provide a method for manufacturing the separation membrane. It will be readily apparent that the 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 a separator for an electrochemical device, the separator comprising: a porous substrate having a plurality of pores; and a porous inorganic coating layer formed on at least one side or both sides of the porous substrate and comprising a plurality of inorganic particles and a binder resin located on some or all of the surfaces of the inorganic particles to connect and fix the inorganic particles. including, [12] The weight of the inorganic particles is 50% by weight or more relative to 100% by weight of the total inorganic coating layer, [13] The separation membrane has a ratio (A) of 70% or more according to [Equation 1] below. [14] [Formula 1] [15] Ratio (A)(%) = [(Initial breakdown voltage before compression - breakdown voltage after compression)/(Initial breakdown voltage before compression)] X 100 [16] In [Equation 1], the initial breakdown voltage before compression means the voltage at the point where a short circuit occurs when the separator is boosted at a predetermined speed by applying a DC current, and the breakdown voltage after compression is 1 MPa for the separator It means a voltage at a point where a short circuit occurs when the voltage is increased at a predetermined speed by applying a DC current while applying pressure in the range of 10 MPa to 10 MPa. [17] In a second aspect of the present invention, in the first aspect, in the separator, when observed from the surface of the inorganic coating layer, secondary particles do not exist, or the diameter of the observed secondary particles is 50 μm or less, The secondary particles are aggregates in which a plurality of primary particles are gathered and aggregated. [18] In a third aspect of the present invention, in the first or second aspect, when the separator is observed from the surface of the inorganic coating layer, secondary particles do not exist, or the diameter of the observed secondary particles is 50 μm or less and the height protruding from the surface of the separation membrane is within 3 μm, and the secondary particles are aggregates in which a plurality of primary particles are aggregated. [19] In a fourth aspect of the present invention, in any one or more aspects of the first to third aspects, the separator has an adhesive force between the separator and the electrode of 15gf/25mm to 200gf/25mm. [20] In a fifth aspect of the present invention, in any one or more aspects of the first to fourth aspects, the binder resin includes a fluorine-based binder resin, and the fluorine-based binder resin includes a polyvinylidene fluoride homopolymer, polyvinylidene Fluoride-hexafluoropropylene (polyvinylidene fluoride-co-hexafluoropropylene), polyvinylidene fluoride-trichloroethylene (polyvinylidene fluoride-co-trichloroethylene) and polyvinylidene fluoride-chlorotrifluoroethylene (polyvinylidene fluoride) -co-chlorotrifluoroethylene), any one selected from the group consisting of, or a mixture of two or more thereof. [21] A sixth aspect of the present invention, in the fifth aspect, the fluorine-based binder resin has a molecular weight of 200,000 to 1.5 million. [22] In a seventh aspect of the present invention, in the sixth aspect, the fluorine-based binder resin is PVDF-HFP, and the degree of substitution of HFP is 3 wt% to 30 wt%. [23] An eighth aspect of the present invention relates to an electrochemical device, wherein the electrochemical device includes an anode, a cathode, and a separator interposed between the anode and the cathode, wherein the separator is disposed on any one of the first to seventh aspects will follow [24] In a ninth aspect of the present invention, in the eighth aspect, the electrochemical device is a lithium secondary battery. [25] A tenth aspect of the present invention relates to a method for manufacturing a separator according to the present invention, the method comprising: preparing a composition for forming an inorganic coating layer including a solvent, inorganic particles and a binder resin; and applying the composition to the surface of the porous substrate and drying the composition, wherein the composition is prepared by adding inorganic particles and a binder resin to a solvent and stirring, and the obtained composite particles in the composition have a particle diameter (D50) At least one condition of 2.5 μm or less and the particle diameter (D 99 ) is 35 μm or less, and the composite particle is a floc formed by agglomeration of inorganic particles and/or binder resin in the composition. [26] In an eleventh aspect of the present invention, in the tenth aspect, the binder resin includes a fluorine-based binder resin, and the fluorine-based binder resin includes a polyvinylidene fluoride homopolymer, polyvinylidene fluoride-hexafluoropropylene ( group consisting of polyvinylidene fluoride-co-hexafluoropropylene), polyvinylidene fluoride-trichloroethylene and polyvinylidene fluoride-co-chlorotrifluoroethylene Any one selected from or a mixture of two or more thereof. [27] A twelfth aspect of the present invention, in the eleventh aspect, the fluorine-based binder resin has a molecular weight of 200,000 to 1.5 million. [28] In a thirteenth aspect of the present invention, in the twelfth aspect, the fluorine-based binder resin is PVDF-HFP, and the degree of substitution of HFP is 3 wt% to 30 wt%. [29] Effects of the Invention [30] The separator for an electrochemical device according to the present invention has a small content of secondary particles in which inorganic particles are aggregated in the inorganic coating layer. In particular, the amount of secondary particles protruding more than a predetermined height to the surface of the separation membrane is small. As such, when inorganic particles are uniformly distributed without agglomeration in the inorganic coating layer and the separator according to the present invention is applied to a battery, the pressure is evenly distributed over the entire surface of the separator when pressure is generated in the battery due to charging and discharging of the battery to prevent deformation of the separator. can be minimized On the other hand, when a porous film made of a polymer material is used as the separator substrate, the tendency for pressure to be intensively applied to the local area of ​​the separator substrate by the secondary particles is lowered, so that damage to the separator substrate is reduced, and thus the short circuit occurrence rate is lowered. [31] Brief description of the drawing [32] 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 to emphasize a clearer description. [33] 1 is a schematic view of a cross-section of a conventional separation membrane, and it is schematically shown that inorganic particles are aggregated to form secondary particle aggregates remaining in the separation membrane. [34] Figure 2 schematically shows a cross-section of a separator according to an embodiment of the present invention. [35] 3 is a schematic view schematically showing a cross-section of a separator in which an electrode bonding portion is formed in one embodiment of the present invention. [36] 4 is an SEM image of a surface of a separator according to an embodiment of the present invention. [37] 5 is an SEM image of the surface of the separator according to Comparative Example 1 of the present invention. [38] Modes for carrying out the invention [39] Hereinafter, the present invention will be described in detail. The terms or words used in the present specification and claims should not 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. [40] [41] Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. [42] [43] 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. [44] [45] Throughout this specification, the description of “A and/or B” means “A or B or both”. [46] [47] The present invention relates to a separator for an electrochemical device. 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. In a specific embodiment of the present invention, the secondary battery may be a lithium ion secondary battery. [48] [49] Separation membrane according to an aspect of the present invention, a porous substrate having a plurality of pores; and a porous inorganic coating layer formed on at least one or both sides of the porous substrate and comprising a plurality of inorganic particles and a binder resin located on some or all of the surfaces of the inorganic particles to connect and fix the inorganic particles. include Here, the weight of the inorganic particles with respect to 100% by weight of the total inorganic coating layer may be 50% by weight or more. [50] In addition, in the present invention, the separation membrane is characterized in that the dielectric breakdown voltage is high. In a specific embodiment, in the separator, the ratio (A) of the breakdown voltage after compression to the breakdown voltage before compression is 70% or more. The ratio (A) may be calculated through the following [Equation 1]. [51] [52] [Formula 1] [53] Ratio (A)(%) = [(Initial breakdown voltage before compression - breakdown voltage after compression)/(Initial breakdown voltage before compression)] X 100 [54] [55] The initial breakdown voltage before compression means a voltage at a point where a short circuit occurs when the voltage is raised at a predetermined speed by applying a DC current to the separator, which is the breakdown voltage measurement object. The initial breakdown voltage before compression may be measured under a temperature condition of 70°C to 90°C. In addition, the DC current may be applied with a current of 0.1 mA or more and may be boosted at a rate of 10V/s to 150V/s. In this case, the voltage may be 3 kV, and the ramp up time may be 30 s. [56] In addition, the breakdown voltage after compression means a voltage at a point where a short circuit occurs when the voltage is raised at a predetermined speed by applying a DC current while pressing the separator in the range of 1 MPa to 10 MPa. The breakdown voltage after the compression may be measured under a temperature condition of 70°C to 90°C. In addition, the DC current may be applied with a current of 0.1 mA or more and may be boosted at a rate of 10V/s to 150V/s. In this case, the voltage may be 3 kV, and the ramp up time may be 30 s. [57] In a specific embodiment of the present invention, the initial breakdown voltage before compression is a DC current of 0.5mA under a temperature condition of 70°C to 90°C when stepping up at a rate of 100V/s (voltage 3kV, ramp up time 30s) It means the voltage at the point where the short circuit occurs. In addition, in a specific embodiment of the present invention, the breakdown voltage after compression is 100V/s (voltage 3kV, It means the voltage at the point where the short circuit occurs when the voltage is boosted at the rate of ramp up time 30s). [58] [59] On the other hand, in the present invention, the dielectric breakdown voltage is the highest voltage that an insulator can withstand, and dielectric breakdown means that when a voltage exceeds a certain value when a voltage is applied to an insulator, the insulation is destroyed and insulation performance is lost. That is, by measuring the breakdown voltage of the separator, the withstand voltage characteristic can be confirmed. In one embodiment of the present invention, the breakdown voltage can be confirmed by placing a separator that is an insulator between two conductors and measuring the voltage at the point where dielectric breakdown occurs by applying a voltage. For example, this breakdown voltage can be measured with an AC/DC/IR Hi-Pot tester. Specifically, the porous substrate is disposed between the aluminum lower plate jig and the cylindrical electrode, and the DC current is set to 0.5 mA, and the voltage rises to 100V/s (voltage 3kV, ramp up time 30s). When the experiment starts, the measurement is completed when a short circuit occurs as the voltage rises, and the voltage at that time is defined as the breakdown voltage. Here, when measuring the dielectric breakdown voltage according to the compression of the separator, a pressure in a predetermined range may be applied to the separator as described above. [60] [61] Meanwhile, in one embodiment of the present invention, the separator has an adhesive force between the separator and the electrode (electrode adhesion) of 15 gf/25 mm to 200 gf/25 mm. [62] [63] The reason that the separator according to the present invention has a high breakdown voltage and/or the above-described electrode adhesion even after compression is due to the low content of the secondary particles of inorganic particles in the inorganic coating layer. In particular, it is because the separation membrane has a uniform surface by controlling the protrusion of the secondary particles to the outside of the surface of the inorganic coating layer. [64] [65] In one embodiment of the present invention, in the separator, when observed from the surface of the inorganic coating layer, secondary particles are not observed, or the diameter of the observed secondary particles is 50 μm or less. Preferably, no observed secondary particles are observed, or the diameter of the observed secondary particles is 30 μm or less. More preferably, no secondary particles are observed or the diameter of the observed secondary particles is 10 μm or less. That is, in the inorganic coating layer according to the present invention, secondary particles are not observed when observed from the surface thereof, or even if secondary particles are present, the diameter of the secondary particles does not exceed 50 μm, preferably does not exceed 30 μm. or, more preferably, it does not exceed 10 μm. The diameter means the longest diameter of each particle. [66] In a specific embodiment of the present invention, in the separator of the present invention, the diameter of the secondary particles observed when observed from the surface of the inorganic coating layer on the basis of 1.5 x 2 cm is 50 μm or less, preferably 30 μm or less, More preferably, it is 30 or less pieces that are 10 micrometers or less, Preferably it is 10 or less. Furthermore, in the separation membrane, when observed from the surface of the inorganic coat layer, secondary particles are not observed or the diameter of the observed secondary particles is controlled within the above range, and the height protruding from the separation membrane surface is within 3 μm. That is, when observed from the surface of the inorganic coating layer, secondary particles are not observed or the protrusion height of the observed secondary particles does not exceed 3 μm. [67] [68] In one embodiment of the present invention, the surface observation of the inorganic coating layer can be measured using a measuring device (X100 times) such as FESEM-Optical profiler to measure the diameter and the protrusion height. A method of measuring the maximum-minimum height may be applied to the measurement of the protrusion height of the secondary particles. The height of the secondary particles may be calculated based on the portion where the step difference between the maximum height and the minimum height is greatest when the optical profiler is measured. [69] In the present invention, the secondary particles refer to an agglomeration of two or more independent independent primary particle-type inorganic particles, and are distinguished from those in which the independent particles are mutually bound by a binder resin. 1 shows a cross-section of a separator according to the prior art, and schematically shows that the secondary particle-type aggregates 123 in which inorganic particles are aggregated remain. On the other hand, Figure 2 schematically shows a cross-section of the separator according to an embodiment of the present invention, and the inorganic particles are not aggregated and are uniformly distributed in the inorganic coating layer of the separator in the state of primary particles 122. [70] In one embodiment of the present invention, the inorganic coating layer may exhibit a state in which inorganic particles are mutually bound to each other through a polymer resin as a medium, and pores are formed by interstitial volume between the inorganic particles. can be In the present specification, the interstitial volume refers to a space defined by inorganic particles substantially interfacing in a closed packed or densely packed structure of inorganic particles. [71] On the other hand, in the present invention, the inorganic coating layer is provided with an electrode bonding portion 121 having a high content of the binder resin on the surface of the inorganic coating layer from the characteristics of a manufacturing method to be described later. 3 is a schematic view showing the cross-sectional structure of the separator 100 according to an embodiment of the present invention. Referring to this, in the separator of the present invention, the inorganic coating layer 120 is formed on the surface of the separator substrate 110, and the binder resin is distributed in a high concentration in the surface layer portion of the inorganic coating layer compared to other portions. In the present specification, for convenience of explanation, a portion of the surface layer in which the binder resin is distributed in a high concentration is referred to as an 'electrode adhesive part 121 '. In one embodiment of the present invention, the electrode bonding portion is a result of migration of the binder resin to the surface layer portion by a manufacturing method such as humidified phase separation to be described later. Therefore, the electrode bonding portion is not physically separated from the inorganic coating layer, but is integrally and inseparably coupled to the surface portion of the inorganic coating layer as a part of the inorganic coating layer. The electrode bonding portion is a result of humidification phase separation, and the thickness of the electrode bonding portion may not be constant. In one embodiment of the present invention, a portion containing 70 wt% or more, preferably 85 wt% or more of the binder resin from the top based on the thickness direction of the inorganic coating layer may be divided into the electrode bonding portion. Meanwhile. In the present specification, each reference numeral may be commonly applied to FIGS. 1 to 3 . [72] Meanwhile, in the present invention, the total thickness of the porous coating layer based on both sides of the separator substrate may be appropriately adjusted in the range of 2 μm to 10 μm or less. [73] The inorganic particles based on the total weight of the inorganic coating layer may be 50% by weight or more, preferably 70% or more. Meanwhile, the inorganic particles may be included in the inorganic coating layer in an amount of 97% by weight or less. When the weight of the inorganic particles is less than 50% by weight, an excess of the binder resin may be present in the pores of the inorganic coating layer, thereby reducing the pore size and porosity. On the other hand, when it exceeds 3% by weight, the amount of the binder resin is too small, and the peeling resistance and/or electrode adhesion of the inorganic coating layer may be reduced. The peeling resistance refers to the adhesion between the separator substrate and the inorganic coating layer, and the electrode adhesion refers to the adhesion between the separator and the electrode. [74] In one embodiment of the present invention, the inorganic coating layer may include a fluorine-based binder resin as a binder resin. The fluorine-based binder resin may include a polyvinylidene fluoride (PVdF)-based polymer. Such PVdF-based polymers are not particularly limited, but polyvinylidene fluoride homopolymer, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene -co-trichloroethylene) and polyvinylidene fluoride-chlorotrifluoroethylene (polyvinylidene fluoride-co-chlorotrifluoroethylene), and the like, and may include at least one selected from among them. In addition, a PVdF-based polymer including a vinylidene fluoride repeating unit (A) and another repeating unit copolymerizable with the repeating unit (B) may be used. [75] In one embodiment of the present invention, the fluorine-based binder preferably has a molecular weight (Mw) of 200,000 to 1.5 million. On the other hand, in the case of PVDF-HFP, wherein the fluorine-based binder is a copolymer further comprising a repeating site such as a repeating unit (B) other than the vinylidene fluoride repeating unit (A), for example, hexafluoropropylene (HFP), the degree of substitution of HFP may have a range of 3 wt% to 30 wt%. [76] In the present invention, the molecular weight (Mw) means a weight average molecular weight. In one embodiment of the present invention, the molecular weight (Mw) may be measured using gel permeation chromatography (GPC). For example, a sample of about 1000 ppm is prepared by diluting 200 mg of a polymer resin for molecular weight measurement in 200 ml of tetrahydrofuran (THF), etc. . Meanwhile, the degree of substitution may be measured by a method such as 1H-NMR using Varian 500 MHz. [77] Meanwhile, if necessary, in addition to the above-described fluorine-based binder, the binder resin may further include a second binder resin such as an acrylic polymer having adhesiveness. The second binder resin is preferably controlled in a range of 3 wt% to 20 wt% based on 100 wt% of the total binder resin. For example, the second binder resin may be included in 5 wt% or more or 10 wt% or more within the above range. As the second binder resin, polyacrylate, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate ), ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate pro Cypionate (cellulose acetate propionate), cyanoethylpullulan (cyanoethylpullulan), cyanoethylpolyvinylalcohol (cyanoethylpolyvinylalcohol), cyanoethylcellulose (cyanoethylcellulose), cyanoethylsucrose (cyanoethylsucrose), pullulan (pullulan) and carro and carboxyl methyl cellulose. [78] [79] In the present invention, the inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are not particularly limited as long as oxidation and/or reduction reactions do not occur in the operating voltage range of the applied electrochemical device (eg, 0-5V based on Li/Li+). In particular, when inorganic particles having a high dielectric constant are used as the inorganic particles, the ionic conductivity of the electrolyte can be improved by contributing to an increase in the degree of dissociation of an electrolyte salt, such as a lithium salt, in a liquid electrolyte. Non-limiting examples of such inorganic particles include high dielectric constant inorganic particles having a dielectric constant of 5 or more, specifically 10 or more, inorganic particles having lithium ion transport ability, or a mixture thereof. In a specific embodiment of the present invention, non-limiting examples of the inorganic particles include BaTiO 3 , Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT) ), PB(Mg 3 Nb 2/3 )O 3 -PbTiO 3(PMN-PT), Hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2 , AlOOH, Al( OH) 3 , SiC, or mixtures thereof. Meanwhile, in addition to this, lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li x Ti y (PO 4 ) 3 , 050 μm 10 or less 2.7 39.9 31 69.1 Comparative Example 2 >50 μm 10-30 2.9 51.4 29 58.9 Comparative Example 3 >50 μm 30 or more 3.1 58.2 28 43.7 [147] As can be seen in [Table 1], in the case of Examples 1 to 6, in which the particle sizes D 50 and D 99 of the composite particles were controlled within the range of the present invention, the diameter of the secondary particles formed in the inorganic coating layer of the separator was It was confirmed that it was smaller than Comparative Examples 1 to 3. In the case of Examples 1 to 6, even if the secondary particles were present in the inorganic coating layer, it was observed that the diameter was 30 μm or less. In particular, Examples 1 to 3 were observed to have a diameter of 10 μm or less even if secondary particles were present. However, in the case of Comparative Examples 1 to 3, secondary particles exceeding 50 μm were observed. In addition, in the case of Examples 1 to 6, it was confirmed that the A value, which is the ratio of dielectric breakdown voltage before and after compression, was 70% or more, which was superior to those of Comparative Examples 1 to 3. Claims [Claim 1] A separator for an electrochemical device, the separator comprising: a porous substrate having a plurality of pores; and a porous inorganic coating layer formed on at least one side or both sides of the porous substrate and comprising a plurality of inorganic particles and a binder resin located on some or all of the surfaces of the inorganic particles to connect and fix the inorganic particles. Including, the weight of the inorganic particles relative to the total 100% by weight of the inorganic coating layer is 50% by weight or more, and the separator has a ratio (A) according to the following [Equation 1] of 70% or more: [Formula 1] Ratio (A)(%) = [(Initial breakdown voltage before compression - breakdown voltage after compression)/(Initial breakdown voltage before compression)] X 100 In Formula 1 above, the first breakdown voltage before compression means the voltage at the point where a short circuit occurs when the separator is boosted at a predetermined speed by applying a DC current, and the breakdown voltage after compression is a predetermined voltage by applying a DC current while pressing the separator in the range of 1 MPa to 10 MPa. In case of step-up at speed, it means the voltage at the point where a short circuit occurs. [Claim 2] According to claim 1, wherein the separation membrane, when observed from the surface of the inorganic coating layer, secondary particles do not exist, or the diameter of the observed secondary particles is 50㎛ or less, the secondary particles are a plurality of primary particles A separation membrane for an electrochemical device, which is an agglomerated aggregate of . [Claim 3] The method according to claim 1, wherein, when the separator is observed from the surface of the inorganic coating layer, secondary particles do not exist, or the diameter of the observed secondary particles is 50 μm or less and the height protruding from the surface of the separator is 3 μm or less. and the secondary particle is an agglomerate in which a plurality of primary particles are gathered and aggregated, the separator for an electrochemical device. [Claim 4] The separator for an electrochemical device according to claim 1, wherein the separator has an adhesive force between the separator and the electrode of 15 gf/25 mm to 200 gf/25 mm. [Claim 5] According to claim 1, wherein the binder resin comprises a fluorine-based binder resin, the fluorine-based binder resin is polyvinylidene fluoride homopolymer, polyvinylidene fluoride-hexafluoropropylene (polyvinylidene fluoride-co-hexafluoropropylene), poly Any one or two of them selected from the group consisting of vinylidene fluoride-trichloroethylene and polyvinylidene fluoride-co-chlorotrifluoroethylene A separator for an electrochemical device comprising the above mixture. [Claim 6] The separator for an electrochemical device according to claim 5, wherein the fluorine-based binder resin has a molecular weight of 200,000 to 1.5 million. [Claim 7] The separator for an electrochemical device according to claim 6, wherein the fluorine-based binder resin is PVDF-HFP, and the degree of substitution of HFP is 3 wt% to 30 wt%. [Claim 8] An electrochemical device comprising an anode, a cathode, and a separator interposed between the anode and the cathode, wherein the separator is the separator according to any one of claims 1 to 7. [Claim 9] The electrochemical device according to claim 8, wherein the electrochemical device is a lithium secondary battery. [Claim 10] A method for manufacturing the separator for an electrochemical device according to claim 1, the method comprising: preparing a composition for forming an inorganic coating layer comprising a solvent, inorganic particles, and a binder resin; and applying the Shingi composition to the surface of the porous substrate and drying the composition, wherein the composition is prepared by adding inorganic particles and a binder resin to a solvent and stirring, and the obtained composite particles in the composition have a particle diameter (D50) 2.5 μm or less and particle diameter (D 99 ) is 35 μm or less, and at least one condition is satisfied, and the composite particle is an electrochemical device that is formed by agglomeration of inorganic particles and/or binder resin in the composition. A method for manufacturing a separation membrane for [Claim 11] 11. The method of claim 10, wherein the binder resin comprises a fluorine-based binder resin, wherein the fluorine-based binder resin is polyvinylidene fluoride homopolymer, polyvinylidene fluoride-hexafluoropropylene (polyvinylidene fluoride-co-hexafluoropropylene), poly Any one or two of them selected from the group consisting of vinylidene fluoride-trichloroethylene and polyvinylidene fluoride-co-chlorotrifluoroethylene A method for producing a separator for an electrochemical device comprising the above mixture. [Claim 12] The method of claim 11, wherein the fluorine-based binder resin has a molecular weight of 200,000 to 1.5 million. [Claim 13] The method of claim 12, wherein the fluorine-based binder resin is PVDF-HFP, and the degree of substitution of HFP is 3 wt% to 30 wt%.