Title of the invention: Battery cell including short-circuit inducing member and safety evaluation method using the same Technical field [One] The present invention relates to a battery cell including a short-circuit inducing member and a method for evaluating the safety of a battery due to an internal short circuit using the battery cell. [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0041138 filed on April 9, 2019, and all contents disclosed in the documents of the Korean patent application are included as part of this specification. Background [3] As the price of energy sources rises due to the depletion of fossil fuels and interest in environmental pollution increases, the demand for eco-friendly alternative energy sources is becoming an indispensable factor for future life. In particular, technology development for mobile devices As the demand and demand increase, the demand for secondary batteries as an energy source is rapidly increasing. [4] Typically, in terms of the shape of the battery, 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 a thin thickness. In terms of materials, lithium-ion batteries with high energy density, discharge voltage, and output stability, There is high demand for lithium secondary batteries such as lithium ion polymer batteries. [5] In general, secondary batteries form a positive electrode and a negative electrode by coating an electrode mixture containing an electrode active material on the surface of a current collector, and form an electrode assembly with a separator interposed therebetween, and then a cylindrical or rectangular metal can or an aluminum laminate sheet. It is mounted inside the pouch-shaped case of the electrode assembly, and is manufactured by mainly injecting or impregnating a liquid electrolyte into the electrode assembly or using a solid electrolyte. [6] In addition, secondary batteries are classified according to the structure of the electrode assembly of the anode/separator/cathode structure. Typically, long sheet-shaped anodes and cathodes are wound with a separator interposed between them. Roll (wound type) electrode assembly, stacked (stacked) electrode assembly in which a plurality of anodes and cathodes cut into units of a predetermined size are sequentially stacked with a separator interposed, And a stack/folding electrode assembly in which bi-cells or full cells stacked in a state are wound with a separator sheet. [7] Meanwhile, the electrode generates an electric current through the exchange of ions, and the positive electrode and the negative electrode constituting the electrode have a structure in which an electrode active material is coated on an electrode current collector made of metal. [8] 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, and the positive electrode has a structure in which an active material made of LiCoO 2 , LiMnO 2 , LiNiO 2 etc. is coated on an electrode plate made of aluminum . Done. [9] In order to manufacture a positive or negative electrode, an electrode mixture including an electrode active material is applied to an electrode current collector made of a metal sheet long in one direction. [10] The separator is positioned between the positive electrode and the negative electrode of the battery to insulate, and maintains the electrolyte to provide a path for ion conduction. [11] Such a secondary battery is a rechargeable battery manufactured using a material in which the oxidation-reduction process between the current and the material can be repeated many times. When a reduction reaction is performed on the material by the current, the power is charged and the material is oxidized. When the reaction is carried out, the power is discharged, and electricity is generated as such charge-discharge is repeatedly performed. [12] A lithium secondary battery has a problem of low safety while having excellent electrical characteristics. For example, lithium secondary batteries generate heat and gas due to decomposition reactions of the battery components, such as active materials and electrolytes, in abnormal operating conditions such as overcharging, overdischarging, exposure to high temperatures, and electrical short circuits. The condition of may further accelerate the decomposition reaction and eventually cause ignition or explosion. [13] In addition, it is very important to ensure safety even when an internal short circuit occurs in the battery, and for this, it is important to correctly evaluate the safety of the battery when an internal short circuit occurs. As a safety item for batteries such as lithium-ion secondary batteries, battery evaluation tests that evaluate the heat generation behavior during internal short circuits include, for example, the UL standard for lithium batteries (UL1642), guidelines from the Battery Industry Association (SBA G1101-1997 lithium Secondary battery safety evaluation criteria guideline). [14] Conventionally, in order to induce an internal short circuit, a heating element is placed inside the battery cell and internal heat is generated by the heating element. There was a method of inducing an internal short circuit by inserting a metal material and applying an external force to tear the separator. However, in the case of the first method, the shape of the product actually used is different due to the heating element inside the cell and the external heating source, and in the second method, the actual separator must be modified and chemical treatment is applied to the damaged part. Therefore, there was a problem that the characteristics of the existing products may be different, and the desired reaction may not occur due to side reactions caused by chemical reactions inside the cell. [15] Meanwhile, in US Patent Publication No. 2013-0209841 (Patent Document 1), a copper plate is inserted into a battery cell after perforating a separator as an internal short circuit inducing device of a battery, 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 is disclosed. 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 that the manufacturing process of the internal short-circuit inducing device is complicated and the unit cost is high, and for repeated use, the battery cell must be disassembled again and then reassembled. Detailed description of the invention Technical challenge [16] The present invention is invented to solve the above problems, and provides a test battery cell for evaluating the safety of a battery without physically altering the battery cell structure, and a battery safety evaluation method using the battery cell. There is a purpose to do it. Means of solving the task [17] In order to achieve the above object, the battery cell according to the present invention, [18] anode; cathode; A separation membrane disposed between the anode and the cathode and having at least one perforation portion formed thereon; And a short inducing member disposed on the perforated portion, [19] In this case, the short-circuit inducing member may include a cover part covering the perforated part; And one or two or more magnetic portions disposed on the side surfaces of the cover portion. [20] [21] The short-circuit inducing member is inserted into a test battery cell including a positive electrode, a negative electrode, and a separator, and is interposed between the perforated portion of the separator and the positive electrode, and/or between the perforated portion and the negative electrode of the separator, and is provided by a magnetic field applied from the outside. By moving, it serves to induce an internal short circuit of the test cell. [22] [23] Meanwhile, the cover portion of the short-circuit inducing member must have an area larger than the area of ​​the perforated portion so as to completely cover the perforated portion in order to prevent short circuit by contacting the anode and the cathode through the perforated portion. In addition, the shape of the cover portion is not limited to a shape such as a circle, an oval, a rectangle, a triangle, etc., but must be capable of completely covering the perforated portion while maintaining the insulation state of the cathode and the anode. [24] [25] Therefore, an insulating film may be used for the cover part, and a porous polymer film may be used for internal ion exchange. [26] In addition, the cover portion may be moved according to an external magnetic field, and may include a magnetic material to facilitate movement. In this case, an additional insulating coating may be applied to the surface of the magnetic material so that an unintended short circuit does not occur inside the battery cell due to the magnetic material. [27] [28] However, in order to minimize factors that may affect the evaluation of the internal short circuit inside the battery cell, it is most preferable to use the same material as the separator for the cover part. [29] [30] In addition, at least one magnetic part is attached to an end of the cover part with a binder, and two or more magnetic parts may be attached according to a moving direction. [31] [32] The binder for attaching the magnetic part to the cover part is polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetra It may contain one or more materials selected from the group consisting of fluoroethylene, polyethylene, polypropylene, epoxy resin, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, or copolymers thereof. have. [33] [34] As the magnetic part as described above is attached to the short-circuit inducing member, when a magnetic field is applied from the outside of the battery cell, the short-circuit inducing member may be moved inside the battery cell according to the direction of the magnetic field. [35] [36] In this case, the magnetic part may include one or two or more of metals that exhibit strong magnetic properties when a magnetic field is applied, such as Fe, Ni, and Co. [37] [38] The perforated portion may be formed in the center of the separation membrane, but is not limited thereto, and the position of the perforated portion may be changed according to a desired position to be short-circuited. In addition, it is possible to arbitrarily adjust the position of a short circuit by forming a plurality of perforated portions in a plurality of perforated portions or to simulate a situation in which a short circuit occurs simultaneously in several places. [39] [40] When a plurality of perforated portions are formed as described above, it is preferable that the short-circuit inducing member is also provided in the same quantity as the number of perforated portions formed accordingly. [41] [42] Meanwhile, a method for evaluating safety according to an internal short circuit of a battery using the battery cell may include the following steps. [43] [44] Preparing a separator in which an anode, a cathode, and a perforated portion are formed; [45] Preparing a cover portion and a magnetic portion capable of covering the perforated portion; [46] Manufacturing a short inducing member by attaching the magnetic part to the cover part; [47] Disposing the short inducing member on the perforated portion; [48] Assembling a battery cell including the positive electrode, negative electrode, separator, and short-circuit inducing member; [49] Applying a magnetic field to the short-circuit inducing member from the outside of the battery cell; [50] The step of exposing the perforated portion by moving the short inducing member. [51] [52] When the short-circuit inducing member is moved to expose the perforated portion in the above-described step, the positive electrode and the negative electrode directly contact each other through the exposed perforated portion, thereby inducing an internal short circuit. Effects of the Invention [53] The battery cell including the short-circuit inducing member of the present invention improves the problem of physically deforming the battery cell after the internal short-circuit evaluation test, which was the biggest problem of conventional methods, and induces internal short-circuit in various states and environments without physical change. can do. In addition, since experiments and evaluations are possible without disassembly and reassembly, the process is simple and time and cost can be saved. Brief description of the drawing [54] 1 is a side view schematically showing a battery cell structure provided with a conventional short-circuit inducing member. [55] 2 is a side cross-sectional view schematically showing the structure of a battery cell equipped with a short inducing member according to an embodiment of the present invention. [56] 3 is a perspective view schematically showing the structure of a battery cell equipped with a short inducing member according to an embodiment of the present invention. [57] 4 is a perspective view schematically showing the structure of a battery cell equipped with a short inducing member according to another embodiment of the present invention. [58] 5 is a perspective view schematically showing the structure of a battery cell equipped with a short inducing member according to another embodiment of the present invention. [59] 6 is a schematic diagram showing, step by step, a safety evaluation method using a battery cell having a short inducing member according to an embodiment of the present invention. Mode for carrying out the invention [60] Since the present invention can apply various changes and have various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. [61] In describing each drawing, similar reference numerals have been used for similar elements. In the accompanying drawings, the dimensions of the structures are shown to be enlarged than actual for clarity of the present invention. The terms used to describe various components are provided to aid 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 component. For example, a first component may be referred to as a second component without departing from the scope of the present invention, and similarly, a second component may be named as a first component. Singular expressions include plural expressions unless the context clearly indicates otherwise. [62] As used throughout the specification of the present invention, terms such as "include" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification It is to be understood that the possibility of the presence or addition of other features, numbers, steps, actions, components, parts, or combinations thereof, or any further features, is not preliminarily excluded. [63] Further, when a part such as 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 above", but also the case where there is another part in the middle. Conversely, when a part such as a layer, film, region, plate, etc. is said to be "under" another part, this includes not only the case where the other part is "directly below" but also the case where there is another part in the middle. In addition, in the specification of the present invention, the term “on” may include a case where it is disposed not only on the top but also on the bottom. [64] In the entire specification of the present invention, "covering" means that the exposed part of the object is put on one side so that the object is not exposed and visible. It means an invisible state. For example, "the perforated part is covered with the cover part" means that the perforated part is no longer exposed on one side where the perforated part is covered by the cover part. [65] [66] Hereinafter, the present invention will be described in detail. [67] [68] The internal short-circuit test is a test that evaluates the resistance to internal short-circuit among the safety tests of the 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 decreases, and the test is conducted until the voltage decreases below a certain value to evaluate the presence or absence of rupture, the voltage and temperature of the battery. [69] [70] 1 is a cross-sectional view schematically showing an electrode assembly 100 equipped with a conventional internal short-circuit induction device developed by the American Energy Research Institute (NREL). [71] Referring to FIG. 1, in the conventional short-circuit inducing member, the wax 140 is used as an insulator to prevent the negative electrode and the positive electrode from contacting during normal operation of the battery, and when the battery rises to the melting point of the wax, the wax is removed. An internal short circuit occurs due to contact between the cathode and anode. [72] Specifically, the conventional internal short-circuit inducing device creates a hole in the separator 120 and inserts a block 130 of a metal material such as copper into the hole, and then inserts a wax layer 140 on one side of the metal plate. do. In addition, the aluminum plate 160 is attached to a portion of the separation membrane in which the wax layer is not interposed, and the copper plate 150 is attached to the wax layer 140. [73] As described above, after installing an internal short-circuit inducing device on the separator 120, the separator 120, the cathode 110, and the anode 111 are wound to manufacture an electrode assembly. [74] [75] In a lithium ion secondary battery, a redox reaction occurs when lithium ions move between the negative electrode and the positive electrode, but in the case of a battery equipped with the conventional short-circuit inducing member as described above, the short-circuit inducing member is installed to the aluminum plate and the copper plate. As a result, the movement of lithium ions was impossible, and an unreacted region was formed. Due to the unreacted region, battery performance such as capacity decreases compared to the existing battery, and it is difficult to simulate the exact behavior of the battery when an internal short circuit occurs, so that the accuracy of safety evaluation decreases. In addition, in the case of the internal short-circuit inducing device as shown in FIG. 1, the manufacturing cost is high, and in order to reuse the battery cell after testing by inserting it into a battery cell, it is inconvenient to disassemble and reassemble the battery cell. In addition, during the reassembly process, the structure of the battery cell may be deformed, which may cause safety problems. [76] [77] 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 specific temperature or higher, and shape memory inserted inside the battery cell There is a risk of the battery cell structure being distorted due to the physical change of the alloy. [78] [79] In addition, there are known methods such as nail penetration test and crush test, but these are irreversibly permanently deforming the battery cell itself, and there is a problem that the battery cell must be newly manufactured every time. [80] [81] The battery cell including the short-circuit inducing member according to the present invention is a further improvement of the above-described prior art, and the short-circuit inducing member includes a cover part made of a porous polymer material and a magnetic part containing a magnetic material. [82] [83] The battery cell into which the short-circuit inducing member is inserted according to the present invention has a structure in which an electrode assembly wound with a positive electrode and a negative electrode, and a separator having a short-circuit inducing member interposed between the positive electrode and the negative electrode is embedded in the battery case, and has a cylindrical structure. There is no limitation on the shape of a battery, such as a battery, a pouch-type battery, a prismatic battery, or a coin-type battery, but a pouch-type battery was used in an embodiment of the present invention. [84] The electrode assembly has a structure that is impregnated with a lithium salt nonaqueous electrolyte in a state in which a negative electrode and a positive electrode are alternately stacked with a separator interposed between the electrodes. The secondary battery electrode may be prepared by applying an electrode mixture containing an electrode active material on a current collector and drying it. The electrode mixture may optionally further include a binder, a conductive material, a filler, and the like, if necessary. [85] 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 changes to the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Surface treatment of carbon, nickel, titanium, silver, or the like may be used on the surface of. The current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on its surface, and various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics are possible. [86] In the case of a negative electrode current collector sheet, it is generally made to have a thickness of 3 to 500 µm. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes to the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel For example, carbon, nickel, titanium, silver, etc. surface-treated, aluminum-cadmium alloy, etc. may be used. In addition, like the positive electrode current collector, it is possible to strengthen the bonding strength of the negative electrode active material by forming fine irregularities on the surface thereof, and it may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics. [87] In the present invention, the positive electrode active material is a material capable of causing an electrochemical reaction, as a lithium transition metal oxide, containing two or more transition metals, and, 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 (where M = Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn or Ga, and including one or more 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 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) of 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, and the like) represented by olivine-based lithium metal phosphate, and the like, but are not limited thereto. [88] Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite-based 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' : Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogen, metal complex oxides such as 0 [157] 100: electrode assembly [158] 110: cathode [159] 111: anode [160] 120: separator [161] 130: block [162] 140: wax layer [163] 150: copper plate [164] 160: aluminum plate [165] 200: battery cell [166] 210: pouch [167] 220: cathode [168] 230: separator [169] 231: perforated part [170] 240: anode [171] 250: cover part [172] 251: magnetic part Claims [Claim 1] anode; cathode; A separation membrane disposed between the anode and the cathode and having at least one perforation portion formed thereon; And a short inducing member disposed on the perforated portion, wherein the short inducing member includes a cover portion covering the perforated portion; And one or two or more magnetic parts disposed on side surfaces of the cover part. [Claim 2] The battery cell of claim 1, wherein the short inducing member is disposed between the positive electrode and the separator, or between the negative electrode and the separator. [Claim 3] The battery cell according to claim 1, wherein an area of ​​the cover part is larger than an area of ​​the perforated part. [Claim 4] The battery cell according to claim 1, wherein the cover part is made of one or a combination of two or more selected from the group consisting of an insulating film, a porous polymer film, and a magnetic material. [Claim 5] The battery cell according to claim 1, wherein the cover part is made of the same material as the separator. [Claim 6] The battery cell according to claim 1, wherein the magnetic part is attached to the cover part by a binder. [Claim 7] The method of claim 6, wherein the binder is polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoro. Ethylene, polyethylene, polypropylene, epoxy resin, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, or a copolymer thereof, characterized in that it comprises one or two or more materials selected from the group consisting of Battery cell. [Claim 8] The battery cell according to claim 1, wherein the position of the short-circuit inducing member is moved by a magnetic field applied from the outside of the battery cell. [Claim 9] The battery cell according to claim 1, wherein the magnetic part comprises one or more magnetic materials selected from the group consisting of Fe, Ni, and Co. [Claim 10] The battery cell of claim 1, wherein the short-circuit inducing member is provided in the same quantity as the number of perforations formed in the separator. [Claim 11] Preparing a separator in which an anode, a cathode, and a perforated portion are formed; Preparing a cover portion capable of covering the magnetic portion and the perforated portion; Manufacturing a short inducing member by attaching the magnetic part to the cover part; Disposing the short inducing member on the perforated portion; Assembling a battery cell including the positive electrode, negative electrode, separator, and short-circuit inducing member; Applying a magnetic field to the short-circuit inducing member from the outside of the battery cell; A method for evaluating safety according to an internal short circuit of a battery comprising; moving the short-circuit inducing member to expose the perforated portion.