[One]The present invention relates to an electrochemical device including a separator having a through-hole formed thereon, a through-hole cover material and a spacer, and a method for evaluating the safety of an energy storage device due to an internal short circuit using the electrochemical device. [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0096020 on August 7, 2019, and all contents disclosed in the documents of the Korean patent application are incorporated as a part of this specification. background [3] As the price of energy sources increases due to the depletion of fossil fuels and interest in environmental pollution is increased, the demand for eco-friendly alternative energy sources is becoming an indispensable factor for future life, and in particular, technology development for mobile devices. As energy consumption increases, the demand for secondary batteries as an energy source is rapidly increasing. [4] Representatively, in terms of battery shape, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with thin thickness, and in terms of materials, lithium ion batteries with high energy density, discharge voltage, and output stability, Demand for lithium secondary batteries such as lithium ion polymer batteries is high. [5] In general, secondary batteries apply an electrode mixture containing an electrode active material to the surface of a current collector to form a positive electrode and a negative electrode, and a separator is interposed therebetween to make an electrode assembly, then a cylindrical or prismatic metal can or aluminum laminate sheet It is mounted inside the pouch-type case of the electrode assembly, mainly by injecting or impregnating a liquid electrolyte or using a solid electrolyte. [6] In addition, secondary batteries are classified according to the structure of the electrode assembly of the positive electrode/separator/negative electrode structure. Typically, a jelly-like structure in which a long sheet-shaped positive electrode and negative electrode are wound with a separator interposed therebetween. A roll (winding type) electrode assembly, a stack type (stacked type) electrode assembly in which a plurality of positive and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, a predetermined unit of positive and negative electrodes interposed with a separator A stack/folding type electrode assembly having a structure in which bi-cells or full cells stacked in a state of being stacked in a separator sheet are wound. [7] On the other hand, the electrode generates a current through the exchange of ions, and the positive and negative electrodes constituting the electrode have a structure in which an electrode active material is applied to an electrode current collector made of a metal. [8] [9] In general, the negative electrode has a structure in which a carbon-based active material is coated on an electrode plate made of copper or aluminum, etc., and the positive electrode has a structure in which an electrode plate made of aluminum, etc. is coated with an active material made of LiCoO 2 , LiMnO 2 , LiNiO 2 , etc. is done [10] In order to manufacture a positive electrode or a negative electrode in this way, an electrode mixture including an electrode active material is applied to an electrode current collector made of a long metal sheet in one direction. [11] The separator is located between the anode and the cathode of the battery to insulate it, and to maintain the electrolyte to provide a path for ion conduction. [12] This secondary battery is a rechargeable battery manufactured using a material in which the redox process between current and material can be repeated in many ways. When the power is discharged, such charge-discharge is repeatedly performed to generate electricity. [13] Lithium secondary batteries have a problem of low safety while having excellent electrical characteristics. For example, in a lithium secondary battery, under abnormal operating conditions such as overcharge, overdischarge, exposure to high temperature, and electrical short circuit, decomposition reactions of active materials and electrolytes, which are battery components, are induced to generate heat and gas, resulting in high temperature and high pressure The condition of further promotes the decomposition reaction, eventually resulting in ignition or explosion. [14] Also, it is very important to secure the safety even when an internal short circuit occurs in the battery, and for this purpose, it is important to correctly evaluate the safety of the battery when an internal short circuit occurs. As a safety item of batteries such as lithium ion secondary batteries, the battery evaluation test for evaluating the exothermic behavior during internal short circuit is, for example, the UL standard for lithium batteries (UL1642), the guidelines from the Battery Industry Association (SBA G1101-1997 lithium Secondary battery safety evaluation standard guidelines), etc. [15] Conventionally, in order to induce an internal short circuit, a method in which a heating element is put inside the battery cell and internal heat is generated by the heating element, a method in which an internal separator is pre-drilled and chemical treatment is performed on the part to melt at a constant temperature, There was a method of inserting a metal material and applying an external force to tear the separator and induce an internal short circuit. However, in the case of the first method, the actual product and shape are different due to the heating element inside the cell and the external heating source. Due to this, the characteristics of existing products may be different, and there was a problem that a desired reaction may not occur due to a side reaction caused by the chemical reaction inside the cell. [16] On the other hand, in US Patent Publication No. 2013-0209841 (Patent Document 1), as a device for inducing an internal short circuit of a battery, a copper plate is inserted into the battery cell after the separator is perforated, and copper and aluminum plates are added to both sides of the separator, and then the copper plate and the separator , or a device for inducing a short circuit inside a battery cell in which a wax layer is installed between an aluminum plate and a separator. When the temperature rises above the melting point of the wax layer in the internal short circuit inducing device, the wax layer is removed, and the anode and the cathode are electrically connected by a copper plate and an aluminum plate, thereby causing an internal short circuit. However, this method has a problem in that the manufacturing process of the internal short circuit inducing device is complicated and the unit cost is high, and in order to use it repeatedly, the battery cell must be disassembled and reassembled again. DETAILED DESCRIPTION OF THE INVENTION technical challenge [17] The present invention was devised to solve the above problems, and without physically deforming the battery cell structure, an electrochemical device for evaluating the safety of an energy storage device, and the safety of an energy storage device using the electrochemical device The purpose is to provide an evaluation method. means of solving the problem [18] In order to achieve the above object, the electrochemical device according to the present invention, [19] Including a structure in which an anode, a separator, and a cathode are sequentially stacked, wherein the separator is a structure in which one or more through-holes communicating the anode and the cathode are formed, [20] At least one interface between the positive electrode and the separator and between the negative electrode and the separator includes a spacer formed at a position that does not overlap the through hole, [21] The interface on which the spacer is placed may include a through-hole cover material containing a magnetic material. [22] [23] The through-hole cover material completely covers the through-hole while overlapping the through-hole formed in the separator, thereby physically blocking contact between the anode and the cathode through the through-hole. In addition, one or more spacers may be included in the interface between the anode and the separator or between the cathode and the separator in a form that does not overlap the through hole, and secures a space so that the through hole cover material can be moved inside the electrochemical device. play a role [24] [25] On the other hand, the shape of the through-hole cover material is not limited as long as it can cover the through-holes, but it is preferable that the through-hole cover material has a plate-like shape in order to maximize space efficiency while being able to move within the spacer. [26] [27] In addition, the through-hole cover material may include one or more magnetic materials selected from the group consisting of Fe, Ni, and Co. By including the magnetic material in the through-hole cover material, at a position spaced apart from the electrochemical device It is possible to move the through-hole cover material according to the applied magnetic field. [28] [29] At this time, when the through-hole cover material is plate-shaped, the magnetic material may have a plate-shaped shape similarly, and may be formed in a ring shape to minimize the effect on ionic conductivity. [30] [31] As described above, since the magnetic material may include a conductive metal, it may contact the anode or the cathode at the same time to cause a short circuit. Accordingly, part or all of the outer circumferential surface of the magnetic material may be surrounded by an insulating material. In this case, the insulating material may be a porous polymer membrane, more specifically, may be the same material as the separator. [32] [33] When the direction perpendicular to the direction in which the anode, the cathode, and the separator of the electrochemical device are stacked is referred to as a horizontal direction, the horizontal cross-sectional area of ​​the through-hole cover material is larger than the area of ​​the through-hole formed in the separator. That is, the through-hole cover material should be able to completely cover the through-hole at a position overlapping the through-hole. [34] [35] In addition, the horizontal cross-sectional area of ​​the inside of the spacer is characterized in that larger than the horizontal cross-sectional area of ​​the through-hole cover material. Accordingly, the through-hole cover material is movable within the spacer. [36] [37] On the other hand, the position of the through-hole cover material may be moved by a magnetic field applied from the outside of the electrochemical device. Accordingly, it may overlap the through-hole to completely cover the through-hole, and the anode and the cathode may be in direct contact by exposing the through-hole. It is also possible to cause a short circuit. This positional movement may be reversible. [38] [39] That is, the internal short circuit evaluation method using the electrochemical device according to the present invention can be made of the following steps. [40] First, an electrochemical device including an anode, a cathode, a separator having through-holes formed thereon, a spacer disposed at at least one interface between the anode and the separator, or the cathode and the separator, and a through-hole cover material covering the through-holes is manufactured. [41] Then, a magnetic field is applied to the through-hole cover material at a position spaced apart from the electrochemical device. In this case, the through-hole cover material containing the magnetic material may be moved according to the strength and direction of the applied magnetic field. [42] When the through-hole is exposed by moving the through-hole cover material, the separator through-hole covered by the through-hole cover material is exposed, through which the positive electrode and the negative electrode can directly physically contact, and an internal short circuit can be induced. [43] Through the process described above, it is possible to evaluate the safety due to the internal short circuit by observing changes in the energy storage device such as a secondary battery or a capacitor in which an internal short circuit has occurred. [44] [45] In addition, if the internal structure of the energy storage device is not deformed due to the internal short circuit, it is possible to cover the through hole at a position overlapping the through hole by moving the through hole cover material again. Therefore, the internal short circuit evaluation can be repeatedly performed only by moving the through-hole cover material without separate disassembly or reassembly. Effects of the Invention [46] The electrochemical device for inducing internal short circuit of the present invention improves the problem that the energy storage device is physically deformed after the internal short circuit evaluation test, which is the biggest problem of the conventional methods, and prevents internal short circuit in various states and environments without physical change. can induce In addition, if there is no deformation of the energy storage device after the evaluation of the internal short circuit, the through-hole cover material inside the electrochemical device is moved again to overlap the through-hole of the separator, so that it can be restored to a state in which a short circuit does not occur, so that disassembly and Retesting and evaluation are possible without reassembly. Brief description of the drawing [47] 1 schematically shows the structure of a battery cell including an electrochemical device according to an embodiment of the present invention. [48] 2 schematically shows the structure of a through-hole cover member according to an embodiment of the present invention. [49] 3 schematically shows a structure including an electrochemical device according to another embodiment of the present invention. [50] 4 schematically illustrates a process of moving the through-hole cover material to induce an internal short circuit by moving the through-hole cover material and then moving the through-hole cover material again to cover the through-hole in the electrochemical device of the present invention. Modes for carrying out the invention [51] Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. [52] In describing each figure, like reference numerals have been used for like elements. In the accompanying drawings, the dimensions of the structures are enlarged than the actual size for clarity of the present invention. Terms used to describe various components are for the purpose of helping understanding, and the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The singular expression includes the plural expression unless the context clearly dictates otherwise. [53] As used throughout the specification of the present invention, terms such as "comprises" or "have" are intended to designate the existence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, one It should be understood that it does not preclude the possibility of the presence or addition of or more other features or numbers, steps, operations, components, parts, or combinations thereof. [54] Further, when a part of a layer, film, region, plate, etc. is said to be “on” another part, this includes not only the case where the other part is “directly on” but also the case where there is another part in between. Conversely, when a part of a layer, film, region, plate, etc. is said to be “under” another part, this includes not only cases where it is “directly under” another part, but also cases where another part is in between. In addition, in the specification of the present invention, “on” may include the case of being disposed not only on the upper part but also on the lower part. [55] In the entire specification of the present invention, "covering" means that the exposed part of the object is placed on one side so that the object is not exposed. It means the invisible state. For example, “the through-hole is covered by the through-hole cover material” means that the through-hole cover material is overlapped on the through-hole, and the through-hole portion is no longer exposed on one surface covered with the through-hole cover material. means that [56] [57] Hereinafter, the present invention will be described in detail. [58] [59] The internal short circuit test is a test that evaluates the resistance to internal short circuit among safety tests of a battery, and is a test simulated when the positive and negative electrodes are short-circuited inside the battery. In the internal short circuit test, first, a fully charged evaluation battery is prepared, an internal short circuit is generated, and the behavior of the battery is evaluated. In general, when an internal short circuit occurs, the battery is discharged and the voltage is reduced, and the test is performed until the voltage decreases below a certain value to evaluate the presence or absence of rupture, the voltage and temperature of the battery. [60] [61] As an example of an internal short circuit induction device designed for battery safety evaluation, in the case of an internal short circuit induction device developed by the National Energy Research Institute (NREL), an insulator made of wax is placed between the anode and the cathode to physically separate the anode and the cathode. . Thereafter, when the battery is charged and discharged and the internal temperature of the battery rises to the melting point of the wax, the wax is removed, and the anode and the anode come into direct contact, resulting in a short circuit inside the battery. [62] More specifically, the conventional internal short-circuit induction device perforates a part of the separator to create a hole. After inserting a block of a metal material such as copper into the hole, a wax layer is interposed on one side of the block of the metal material. In addition, the positive electrode plate is attached to a portion of the separator where the wax layer is not interposed, and the negative electrode plate is attached to the wax layer. When the wax layer is removed, the positive electrode, the metal material block, and the negative electrode come into direct contact with each other to cause a short circuit. [63] [64] In a lithium ion secondary battery, an oxidation-reduction reaction occurs as lithium ions move between the negative electrode and the positive electrode. Due to this, the movement of lithium ions was impossible, and an unreacted region was formed. Due to the unreacted region, there is a problem in that the battery performance such as capacity is reduced compared to the conventional battery, and it is difficult to simulate the correct behavior of the battery when an internal short circuit occurs, so that the accuracy of the safety evaluation is reduced. In addition, in the case of the conventional internal short circuit inducing device described above, the manufacturing cost is high, and in order to be reused after being inserted into the battery cell and assembled for testing, the battery cell must be disassembled and reassembled to include the short circuit induction device structure. However, during the reassembly process, the assembly alignment may be misaligned or the battery cell structure may be deformed, which may cause unexpected safety problems. [65] [66] In addition to the above method, there is an internal short circuit test method of a battery cell using a shape memory alloy as described in Patent Document 2, but this also has a limitation that the battery must be heated to a certain temperature or higher, and the shape memory inserted into the battery cell As the shape of the alloy is deformed, there is a risk that other components of the battery cell other than the separator may be distorted. [67] [68] In addition, there are known methods such as a nail penetration test and a crush test, but these are irreversible and permanent deformation of the battery cell itself, and there is a problem in that the battery cell must be newly manufactured for each test. [69] [70] In the present invention, the electrochemical device can be used without limitation in a secondary battery including a positive electrode, a negative electrode and a separator, and an energy storage device such as a capacitor, and is a further improvement of the prior art. [71] [72] Specifically, the electrochemical device of the present invention can be used in an electrode assembly inside a battery cell of a lithium secondary battery, and there is no limitation in the form of a battery such as a cylindrical battery, a pouch-type battery, a prismatic battery, or a coin-type battery. In this example, a pouch-type battery was used. [73] [74] The electrode assembly has a structure in which the negative electrode and the positive electrode are alternately stacked and impregnated in a lithium salt non-aqueous electrolyte with a separator interposed between the electrodes. The electrode for a secondary battery may be manufactured by coating an electrode mixture containing an electrode active material on a current collector and then drying, and the electrode mixture may optionally further include a binder, a conductive material, a filler, and the like, if necessary. [75] In the present invention, the positive electrode current collector is generally made to have a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Carbon, nickel, titanium, silver, etc. surface-treated on the surface of the can be used. The current collector may increase the adhesive force of the positive electrode active material by forming fine irregularities on the surface thereof, and various forms such as a film, sheet, foil, net, porous body, foam body, and nonwoven body are possible. [76] In the case of a sheet for a negative electrode current collector, it is generally made to a thickness of 3 to 500 μm. Such a negative current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel. Carbon, nickel, titanium, silver, etc. surface-treated, aluminum-cadmium alloy, etc. may be used. In addition, like the positive electrode current collector, the bonding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven body. [77] In the present invention, the cathode active material is a material capable of causing an electrochemical reaction, and as a lithium transition metal oxide, includes two or more transition metals, for example, lithium cobalt oxide (LiCoO2) substituted with one or more transition metals. , layered compounds such as lithium nickel oxide (LiNiO2); lithium manganese oxide substituted with one or more transition metals; Formula LiNi 1-y M y O 2 (wherein M = Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn or Ga and includes at least one of the above elements, 0.01≤y≤0.7) Lithium nickel-based oxide represented by; Li 1 + z Ni 1/3 Co 1/3 Mn 1/3 O 2 , Li 1 + z Ni 0.4 Mn 0.4 Co 0.2 O 2 Li, such as 1 + z Ni b Mn c Co 1-(b+c+d) M d O (2-e) A e (where -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2 , 0≤e≤0.2, b+c+d<1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl) a lithium nickel cobalt manganese composite oxide; Formula Li 1+x M+M' y PO 4-z X z , where M = transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5≤x≤+0.5, 0≤y≤0.5, 0≤z≤0.1) olivine-based lithium metal phosphate and the like are mentioned, but are not limited thereto. [78] 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), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me' : metal composite oxides such as Al, B, P, Si, elements of Groups 1, 2, and 3 of the periodic table, halogen; 0 [145] 10: through hole cover material [146] 11: magnetic material [147] 12: insulating film [148] 13: insulating film [149] 100: battery cell [150] 110: positive electrode [151] 120: cathode [152] 130: separator [153] 131: through hole [154] 140: spacer [155] 141: spacer inner space [156] 150: battery case [157] 200: battery cell [158] 210: positive electrode [159] 220: cathode [160] 230: separator [161] 231: through hole [162] 240: spacer [163] 241: spacer inner space [164] 250: battery case WE CLAIMS Including a structure in which an anode, a separator and a cathode are sequentially stacked, wherein the separator has a structure in which one or more through-holes communicating the anode and the cathode are formed, and at least one interface between the anode and the separator and between the cathode and the separator , an electrochemical device comprising a spacer formed at a position not overlapping the through hole, and a through hole cover material containing a magnetic material at an interface on which the spacer is placed. [Claim 2] The electrochemical device according to claim 1, wherein the through-hole cover material has a plate shape. [Claim 3] The electrochemical device according to claim 1, wherein the through-hole cover material comprises one or more magnetic materials selected from the group consisting of Fe, Ni, and Co. [Claim 4] [4] The electrochemical device according to claim 3, wherein the magnetic material has a plate shape or a ring shape. [Claim 5] The electrochemical device according to claim 3, wherein an outer circumferential surface of the magnetic material is surrounded by an insulating material. [Claim 6] The electrochemical device according to claim 4, wherein the insulating material is a porous polymer film. [Claim 7] The electrochemical device according to claim 1, wherein a horizontal cross-sectional area of ​​the through-hole cover material is larger than an area of ​​a through-hole formed in the separator. [Claim 8] The electrochemical device according to claim 1, wherein a horizontal cross-sectional area inside the spacer is larger than a horizontal cross-sectional area of ​​the through-hole cover material. [Claim 9] The electrochemical device according to claim 1, wherein the through-hole cover material is moved by a magnetic field applied from the outside of the electrochemical device. [Claim 10] manufacturing an electrochemical device including an anode, a cathode, a separator having a through-hole formed therein, a spacer disposed at at least one interface between the anode and the separator, or the cathode and the separator, and a through-hole cover material covering the through-hole; applying a magnetic field to the through-hole cover member at a position spaced apart from the electrochemical device; A method for evaluating safety according to an internal short circuit of a battery comprising a; exposing the through-hole by moving the through-hole cover material. [Claim 11] The method of claim 10 , further comprising: exposing the through-hole by moving the through-hole cover material; Then, moving the through-hole cover material to cover the through-hole again; safety evaluation method according to the internal short circuit of the battery further comprising a.