Jig for evaluating the safety of secondary batteries

Abstract

The present invention relates to a jig for evaluating the safety of a secondary battery, comprising: a jig part including a first terminal pin and a second terminal pin that contact an external terminal of a cell; and a plate positioned opposite the jig part and supporting the cell, wherein the jig part includes a main body that is separated and coupled to at least one of the first terminal pin and the second terminal pin that contact the cell.

Description

Technical Field

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0171664, filed with the Korean Intellectual Property Office on December 03, 2021, and all of its contents are incorporated herein by reference.

[0002] The present invention relates to a jig for evaluating the safety of secondary batteries. Specifically, the present invention relates to a jig used when evaluating the safety of large secondary batteries.

Background Art

[0003] In recent years, the demand for portable electronic products such as notebook computers, video cameras, and mobile phones has increased rapidly. As the development of electric vehicles, energy storage batteries, robots, satellites, etc. has become full-scale, research on high-performance secondary batteries that can be repeatedly charged and discharged has been actively conducted.

[0004] Currently commercialized secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among them, lithium secondary batteries have attracted attention due to advantages such as almost no memory effect, free charging and discharging, very low self-discharge rate, and high energy density compared to nickel-based secondary batteries.​​​​​​​In such lithium secondary batteries, lithium oxide and carbon materials are mainly used as the positive electrode active material and negative electrode active material, respectively. A lithium secondary battery comprises an electrode assembly in which a positive electrode plate and a negative electrode plate, each coated with the positive electrode active material and negative electrode active material respectively, are arranged with a separator in between, and an outer casing material that seals and houses the electrode assembly together with the electrolyte.

[0007] On the other hand, lithium secondary batteries are manufactured in various shapes such as cylindrical, rectangular, and pouch types. An example of an electrode assembly used in the cylindrical secondary battery is a jelly roll-shaped electrode assembly formed by coating a current collector with an active material, drying it, and then inserting a separator sheet between a negative electrode sheet and a positive electrode sheet formed by roll pressing and cutting, and then winding it up.

[0008] Generally, in cylindrical rechargeable batteries, a jelly roll made by winding a negative electrode sheet, a positive electrode sheet, and a separator sheet into a circular shape is placed in the battery case, while in rectangular or pouch-type batteries, a jelly roll made by winding a negative electrode sheet, a positive electrode sheet, and a separator sheet into an oval shape is pressed flat before being placed in the battery case.

[0009] The positive electrode lead, welded to the positive electrode current collector of the electrode assembly, is electrically connected to the cap assembly and to a protruding terminal at the upper end of the top cap. The negative electrode lead, welded to the negative electrode current collector, is welded to the sealed end of the case, so that the case itself constitutes the negative electrode terminal. The material of the case is not particularly limited and can be made from stainless steel, steel, aluminum, or any of the equivalents. The assembly of the cylindrical secondary battery is completed when the electrolyte is injected with the electrode assembly housed in the case, and the cap assembly is attached to the open end of the case and sealed.

[0010] To evaluate whether cylindrical rechargeable batteries remain safe after multiple charge / discharge cycles, positive and negative electrode tabs were welded to the external terminals of the batteries, and the positive and negative electrode tabs were connected to a charge / discharge device for safety evaluation.

[0011] However, the increasing size of cylindrical secondary batteries led to an increase in the current applied during charging and discharging. As a result, the high current caused overheating, which resulted in the electrode tabs welded to the external terminals of the secondary battery breaking. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] Focusing on the problems of the prior art described above, the present invention aims to provide a jig used when evaluating the safety of large secondary batteries. [Means for solving the problem]

[0013] One embodiment of the present invention provides a jig for evaluating the safety of a secondary battery, comprising a jig portion including a first terminal pin and a second terminal pin that contact the external terminals of a cell, and a plate positioned opposite the jig portion and supporting the cell, wherein the jig portion includes a body that is separated and connected to at least one of the first terminal pin and the second terminal pin that contact the cell.

[0014] In one embodiment of the present invention, the first terminal pin and the second terminal pin contact the positive terminal portion and the negative terminal portion of the cell, providing a jig for evaluating the safety of a secondary battery.

[0015] In one embodiment of the present invention, the present invention provides a jig for evaluating the safety of a secondary battery, wherein the cell includes an electrode assembly in which a separator and electrodes are wound, a can housing the electrode assembly having an opening on one side and a through hole on the other side, a vent coupled to the opening, and a second electrode terminal coupled to the through hole, and either the first terminal pin or the second terminal pin has a smaller diameter than or the same diameter as the second electrode terminal.

[0016] In one embodiment of the present invention, a jig for evaluating the safety of a secondary battery is provided, wherein one or more of the first terminal pins and the second terminal pins are separated from and connected to the main body by a screw structure.

[0017] In one embodiment of the present invention, the plate provides a jig for evaluating the safety of a secondary battery, which includes an ignition outlet for discharging flames and heat to the outside.

[0018] In one embodiment of the present invention, a jig for evaluating the safety of a secondary battery is provided, further comprising a plate control unit that adjusts the position of the plate to bring the cell and the jig into contact or separate them.

[0019] In one embodiment of the present invention, a jig for evaluating the safety of a secondary battery is provided, further comprising a connecting portion coupled to the jig portion and electrically connecting the cell to a safety evaluation device.

[0020] In one embodiment of the present invention, a jig for evaluating the safety of a secondary battery is provided, wherein the jig portion includes a first terminal pin and a second terminal pin, and the connecting portion includes one or both of a first terminal pin connecting portion connected to the first terminal pin of the jig portion and a second terminal pin connecting portion connected to the second terminal pin of the jig portion.

[0021] In one embodiment of the present invention, a jig for evaluating the safety of a secondary battery is provided, which is equipped with a plurality of the aforementioned plates.

[0022] One embodiment of the present invention provides a jig for evaluating the safety of a secondary battery, further comprising a mounting portion that contacts and supports at least a portion of the cell.

[0023] In one embodiment of the present invention, the aforementioned mounting portion provides a jig for evaluating the safety of a secondary battery, which supports the cell by contacting at least a portion of the side surface of the cell. [Effects of the Invention]

[0024] In the embodiment of the present invention, the jig for evaluating the safety of a secondary battery brings the external terminals of the cell into contact with the terminal pins of the jig via a plate that supports the cell, thus eliminating the need for welding between the cell terminals and the terminal pins of the jig.

[0025] Moreover, when charging and discharging the cell for the safety evaluation of the secondary battery, the present invention can prevent heat generation from occurring at the welded portion between the external terminal of the cell and the terminal pin of the jig due to the high current generated, and prevent disconnection between the external terminal of the cell and the terminal pin of the jig.

Brief Description of the Drawings

[0026] [Figure 1] It is a photograph of a jig for safety evaluation of a secondary battery according to an embodiment of the present invention. [Figure 2] (a) is a side photograph of a jig portion according to an embodiment of the present invention, and (b) is a rear photograph of the jig portion according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view showing a cell according to an embodiment of the present invention. [Figure 4] (a) is a cross-sectional view showing a jig for safety evaluation of a secondary battery according to another embodiment of the present invention, and (b) is a plan view showing the jig portion of the jig for safety evaluation of a secondary battery according to another embodiment of the present invention. [Figure 5] (a) is a photograph provided for a jig for safety evaluation of a secondary battery in a comparative example, and (b) is a photograph provided for a jig for safety evaluation of a secondary battery in an example. [Figure 6] (a) is a graph measuring the applied current according to time in a comparative example, and (b) is a graph measuring the applied current according to time in an example.

Modes for Carrying Out the Invention

[0027] <000011o>The detailed description regarding the present invention is for completely explaining the present invention to those having ordinary knowledge in the industry. Throughout the specification, when a certain part "includes" a certain component or a certain structure and shape is regarded as a "feature", this means that, unless otherwise stated, it does not exclude other components or other structures and shapes, and may include other components, structures and shapes.

[0028] While the present invention may involve various transformations and may have numerous embodiments, this document presents specific embodiments and will provide a detailed explanation in the detailed description. However, this is not intended to limit the scope of the invention by the embodiments, but rather should be understood to include all transformations, equivalents, or substitutes that fall within the spirit and technical scope of the present invention.

[0029] The present invention will be described in detail below with reference to the drawings. However, the drawings are for illustrative purposes only, and the scope of the present invention is not limited by the drawings.

[0030] Figure 1 is a photograph of a safety evaluation jig for a secondary battery according to one embodiment of the present invention; Figure 2(a) is a side view of the jig according to one embodiment of the present invention; Figure 2(b) is a rear view of the jig according to one embodiment of the present invention; and Figure 3 is a cross-sectional view showing a cell 200 according to one embodiment of the present invention.

[0031] The secondary battery safety evaluation jig 100 according to the present invention is used to intentionally ignite a secondary battery for safety evaluation and to analyze the flame duration and temperature of the secondary battery 200. The secondary battery safety evaluation jig 100 includes a jig section 20 and a plate 30.

[0032] The cell 200 according to the present invention may include a secondary battery. In one embodiment, the cell may include an electrode assembly 1, a can 2 in which the electrode assembly 1 is housed, a plurality of current collector plates (positive electrode current collector plate and negative electrode current collector plate, not shown) located on one side and the other side of the electrode assembly 1, respectively, and a vent 3 for sealing the can 2.

[0033] The electrode assembly 1 is a charge-dischargeable power generation element consisting of a laminated structure of electrodes (not shown) and separators (not shown), and may include a jelly roll type structure in which a separator is interposed between long sheet-like electrodes coated with an active material and wound up.

[0034] For example, the electrodes may include a negative electrode and a positive electrode, and the negative electrode, separator, and positive electrode can be sequentially stacked to form an electrode assembly 1. Furthermore, the electrode assembly 1 according to the present invention can be formed by stacking multiple electrode assemblies 1, each in which a negative electrode, separator, and positive electrode are sequentially stacked.

[0035] In one embodiment, the electrode assembly 1 has an active material portion (not shown) along the length of the current collector, and plain portions (not shown) without active material can be located on both sides of the active material portion, i.e., on both sides of the active material portion located in the length direction of the active material portion. Here, the length of the current collector may mean the direction in which the distance between the two ends is longest when the wound electrode assembly 1 is unfolded.

[0036] The active material may include a positive electrode active material and a negative electrode active material. The positive electrode active material may include lithium cobalt oxide, which has a high operating voltage and excellent capacity characteristics; lithium nickel oxide, which has high reversible capacity and facilitates the realization of high-capacity batteries; lithium nickel cobalt oxide, in which part of the nickel is replaced with cobalt; lithium nickel cobalt metal oxide, in which part of the nickel is replaced with manganese, cobalt, or aluminum; lithium manganese-based oxide, which has excellent thermal safety and is inexpensive; and lithium iron phosphorus oxide, which has excellent safety.

[0037] The negative electrode active material may be, for example, a carbon material such as crystalline carbon, amorphous carbon, carbon composite, or carbon fiber, a lithium metal, or a lithium alloy. In this case, the negative electrode active material may further contain, for example, non-graphite-based SiO (silica) or SiC (silicon carbide) for high-capacity design.

[0038] The electrode assembly 1 can be folded towards the center of the electrode assembly 1 by notching the plain sections located at both ends of the electrodes wound on the outermost side of the electrode assembly 1, opposite the winding center (or core section). Alternatively, the entire plain section wound onto the electrode assembly 1 can be notched, and the notched portion can be folded towards the outer edge of the electrode assembly 1.

[0039] In other embodiments, the electrode may include an active material portion and a blank portion on one surface of the current collector. The blank portion may be located at one or more ends of the surface of the current collector, or in an intermediate region.

[0040] Furthermore, the plain surface may be provided with electrode tabs (not shown) on at least a portion of one side. The electrode tabs may be positioned so that part of them is in contact with the plain surface, and part of them protrudes in the width (W) direction of the current collector. The electrode tabs can transmit electrons collected by the current collector to an external circuit.

[0041] In the secondary battery 200 according to the present invention, the electrode assembly 1 may be provided with a core portion (C) formed by removing the winding core from the center. The secondary battery 200 may further include a center pin (not shown) in the core portion (C). The center pin prevents the electrode assembly 1, which is wound in a jelly roll shape, from unraveling and can act as a gas passage inside the cylindrical secondary battery.

[0042] The can 2 may have a columnar structure with an internal space. The can 2 can house an electrode assembly 1, including electrodes and a separator, and an electrolyte (not shown) in its internal space. One side of the can 2 may have an open structure, and the other side may be provided with a through hole (not shown). The through hole may be circular or polygonal, and the diameter or width of the through hole may be less than the diameter of the can 2. Here, one side and the other side of the can 2 refer to the ends located at the top and bottom along the direction of gravity or the central axis of the can 2.

[0043] The can 2 according to the present invention may have a columnar shape in which the diameter is the same or the diameter narrows or widens along the axial direction of the can 2.

[0044] The can 2 according to the present invention may include a beading portion 2a and a crimping portion 2b on which the vent 3 and the first current collector plate 4 are stacked and fixed. The beading portion 2a is formed in an area adjacent to one side of the open can 2 and may have a shape that is press-fitted into the inside of the can 2. The crimping portion 2b can be formed by pressurizing the upper outer wall of the can 2, which is not press-fitted, towards the center of the can 2.

[0045] Furthermore, the secondary battery 200 according to the present invention may further include a gasket (G) that increases the sealing force between the inner surface of the crimping portion 2b and the first current collector plate 4 and the end of the vent 3.

[0046] Can 2 can be made of a lightweight conductive metal material such as aluminum or an aluminum alloy.

[0047] The dimensions of can 2 may be such that the diameter of the circular sections at both ends is 30mm to 55mm and the height is 60mm to 120mm. For example, the diameter × height of the circular section of a cylindrical can may be 40mm × 60mm, 40mm × 80mm, 40mm × 90mm, or 40mm × 120mm.

[0048] The vent 3 is a thin-film structure through which electric current flows and can be located at the opening of the can 2. In one embodiment, the diameter of the vent 3 may be the same as the internal diameter of the can 2. The vent 3 may include a first surface facing the first current collector plate and a second surface facing the first surface. The side surface of the vent 3 can be in contact with the inner surface of the can 2, and the contact surface between the side surface of the vent 3 and the can 2 can be welded to fix the can 2 and the vent. Here, the side surface of the vent 3 means the surface connecting the first surface and the second surface, and the surface located perpendicular to the first surface and the second surface.

[0049] Vent 3 can protrude downwards as it moves from the edge towards the center. In other words, vent 3 can protrude in stages in the direction in which the first current collector plate is located as it moves from the edge towards the center.

[0050] The vent 3 may include one or more vent notches 3a that rupture when the internal pressure of the can 2 exceeds a threshold. The vent notches 3a may be provided on one or more of the first and second surfaces of the vent 3. The vent notches 3a may be provided on the surface of the vent 3 with a continuous or discontinuous circular pattern, a linear pattern, or other pattern. The depth and width of the vent notches 3a may vary depending on the internal pressure of the can 2 when it exceeds 15 kgf / cm². 2 ~35 kgf / cm² 2 It can be formed to burst when it is within a certain range.

[0051] The first current collector plate 4 is located on one side of the electrode assembly 1, between the electrode assembly 1 and the vent 3, and can be electrically connected to the electrode assembly 1 and the vent 3.

[0052] The second current collector plate 5a can be positioned opposite the first current collector plate 4.

[0053] The second current collector plate 5a may be positioned opposite the first current collector plate 4. Furthermore, the secondary battery 200 according to the present invention may further include an insulator (S) between the second current collector plate 5a and the can 2.

[0054] The first current collector plate 4 may further include a first electrode terminal (not shown), and the second current collector plate 5a may include a second electrode terminal 5b. The first and second electrode terminals 5b may be made of a conductive metal material. For example, the first and second electrode terminals 5b may be made of aluminum, but are not limited to aluminum.

[0055] The second electrode terminal 5b is connected to a through-hole in the can 2 and can be electrically connected to the electrode assembly 1. The second electrode terminal 5b can exhibit a different polarity from the can 2. For example, if the can 2 exhibits a negative polarity, the second electrode terminal 5b can exhibit a positive polarity.

[0056] The secondary battery 200 according to the present invention may include a second terminal gasket 5c between the second electrode terminal 5b and the inner surface of the through hole, so that the second electrode terminal 5b exhibits a different polarity from the can 2. The second terminal gasket 5c can be made of a polymer resin that has insulating and elastic properties, thereby preventing contact between the second electrode terminal 5b and the can 2.

[0057] The second terminal gasket 5c can be made of, for example, polypropylene, polybutylene terephthalate, or polyfluoroethylene, but the present invention is not limited to these.

[0058] The jig portion 20 may include one or more first terminal pins 21 and second terminal pins 22 that contact the external terminals of the cell. In one embodiment, the mounting portion 10 may contact the side surface of the cell 200, and one side of the jig portion 20 may be positioned perpendicular to the mounting portion 10.

[0059] The cell 200 according to the present invention may include an external terminal, the external terminal may include a first terminal portion and a second terminal portion. In one embodiment, referring to Figure 4, the first terminal portion may be the second electrode terminal 5b, and the second terminal portion may be the can 2, that is, the can 2 surrounding the second electrode terminal 5b.

[0060] The jig portion 20 includes a first terminal pin 21 and a second terminal pin 22, the first terminal pin 21 and the second terminal pin 22 being able to contact the first and second terminal portions of the cell, respectively. If the first terminal pin 21 is the positive terminal and the second terminal pin 22 is the negative terminal, the first terminal pin 21 can contact the second electrode terminal 5b of the cell 200, and the second terminal pin 22 can contact the can 2 of the cell 200.

[0061] The second electrode terminal 5b can be provided as a projection with a diameter smaller than the diameter of the cell. Therefore, the first terminal pin 21 or the second terminal pin 22 that contacts the second electrode terminal 5b can be provided with a diameter equal to or smaller than that of the second electrode terminal 5b. Here, the diameters of the second electrode terminal 5b, the first terminal pin 21, and the second terminal pin 22 refer to the size of the second electrode terminal 5b, the first terminal pin 21, and the second terminal pin 22. For example, if the second electrode terminal 5b, the first terminal pin 21, and the second terminal pin 22 are circular, it may refer to the diameter distance; if the second electrode terminal 5b, the first terminal pin 21, and the second terminal pin 22 are polygonal shapes other than circles, it may refer to the length of the outer edge of the polygon.

[0062] In other embodiments, the jig portion 20 may have one or more of the first terminal pins 21 and the second terminal pins 22 separated.

[0063] The jig portion 20 may include a first terminal pin 21, a second terminal pin 22 that contact the terminal portion of the cell, and a body (not shown) to which one or more of the first terminal pin 21 and the second terminal pin 22 are separated and connected.

[0064] For example, when the first terminal pin 21 is the positive terminal pin and the second terminal pin is the negative terminal pin, the jig portion 20 can be configured such that the second terminal pin 22 is fixed to the main body, and only the first terminal pin 21 can be separated from / connected to the main body. Alternatively, the jig portion 20 can be configured such that both the first terminal pin 21 and the second terminal pin 22 can be separated from / connected to the main body.

[0065] One or more of the first terminal pin 21 and the second terminal pin 22 can be separated from / connected to the main body by a screw structure. For example, the main body may have one or more screw-shaped grooves on one surface, and the first terminal pin 21 and the second terminal pin 22 may have a protruding connecting portion on one surface with screw threads on its outer surface. Therefore, the groove of the main body and the connecting portion of the first terminal pin 21 or the second terminal pin 22 can be separated / connected by a screw structure.

[0066] The jig portion 20 can be made of brass plated with gold. Furthermore, the jig portion 20 can be treated with an O-ring to reduce contact resistance.

[0067] The plate 30 is located on the other side of the mounting section 10 and can support the cell 200. The plate 30 can be positioned in the opposite direction to the jig section 20 with respect to the cell.

[0068] The plate 30 may include an ignition outlet 31. When a secondary battery is charged / discharged for safety evaluation of the secondary battery, thermal runaway may occur during charging / discharging, generating flames and high temperatures, and the ignition outlet 31 can vent the flames and high temperatures generated in the cell to the outside.

[0069] The safety evaluation jig 100 for secondary batteries according to the present invention is equipped with an ignition outlet 31, so that even when multiple batteries are evaluated simultaneously, flames are discharged through the ignition outlet 31, preventing chain ignition and side rupture.

[0070] The diameter of the ignition outlet 31 may be the same as or smaller than the diameter of the cell placed on the safety evaluation jig 100 for secondary batteries according to the present invention. The plate 30 can support the can 2 by placing the crimping portion 2b of the can 2 on the portion of the plate 30 that does not have the ignition outlet 31. Therefore, even if the diameter of the ignition outlet 31 is the same as that of the can 2, the plate 30 can support the cell.

[0071] In one embodiment, the ignition outlet 31 may have a diameter of 1 mm to 10 mm or less. Preferably, the ignition outlet 31 has a diameter of 2 mm to 8 mm, and more preferably, 2 mm to 5 mm.

[0072] By ensuring the ignition outlet 31 meets the above numerical range, it supports the cell 200 and effectively dissipates the heat of ignition when the cell 200 ignites, thereby maintaining a constant temperature for the cell 200. In other words, because the ignition outlet 31 is wide, it prevents the problem of the cell 200 passing through the ignition outlet 31 when the plate 30 is moved to support the cell 200. Furthermore, because the ignition outlet 31 is narrow, it prevents the heat of ignition from escaping into the ignition outlet 31, or prevents a long delay in the time it takes for the heat of ignition to be ejected to the outside through the ignition outlet 31.

[0073] The plate 30 may consist of one or more plates, where "one or more" may mean one or two or more components. If multiple plates 30 are included, plate connectors connecting the multiple plates may be included. If multiple plates 30 are included, all plates 30 may include an ignition exhaust port 31.

[0074] The safety evaluation jig 100 for secondary batteries according to the present invention may further include a plate control unit 40 that adjusts the position of the plate 30 to bring the cell into contact with or separate the jig portion 20. More specifically, the plate control unit 40 can adjust the height of the plate 30. When the plate control unit 40 adjusts the position of the plate 30 toward the jig portion 20, the terminal portion of the cell and the first terminal pin 21 and second terminal pin 22 of the jig portion can come into contact.

[0075] For example, the plate control unit 40 may include a column with screw threads on its outer surface and a bolt that is screw-connected to the column and adjusts the height of the plate 30. If there are multiple plates 30, the plate control unit 40 may be an extension of the plate connection part.

[0076] Figure 4 is a plan view showing the jig portion 20 of a secondary battery safety evaluation jig 100 according to another embodiment of the present invention. The secondary battery safety evaluation jig 100 according to another embodiment of the present invention can evaluate the safety of multiple cells 200. In this case, the jig portion 20 may include one or more first terminal pins 21 and second terminal pins 22, and one plate 30 may include one or more ignition outlets 31.

[0077] The safety evaluation jig 100 for secondary batteries according to the present invention may further include a mounting section 10.

[0078] The mounting portion 10 can support the cell by contacting at least a portion of it. In one embodiment, the mounting portion 10 can be provided in a form obtained by cutting the outer shape of the cell 200 in the axial direction. Therefore, the mounting portion 10 can support the cell 200 by contacting at least a portion of the side surface of the cell 200. Here, the side surface of the cell 200 may mean the surface excluding the surface located at the top and bottom along the axial direction from the three or four surfaces that constitute the cell 200. For example, if the cell 200 is a cylindrical secondary battery, the mounting portion 10 can be provided in a semi-cylindrical structure obtained by cutting a cylinder once in the axial direction.

[0079] The safety evaluation jig 100 for secondary batteries according to the present invention may further include a connecting portion 50. The connecting portion 50 can be coupled to a part of the jig portion 20, and can electrically connect the safety evaluation device to the cell or the jig portion 20. That is, the connecting portion 50 can be connected to a conductor included in the safety evaluation device, and can electrically connect the cell to the safety evaluation device.

[0080] The connecting portion 50 may contain one or more conductors inside. The connecting portion 50 may also include a connecting portion (not shown) protruding from one side of the connecting portion 50 in order to connect a conductor provided in the safety evaluation device with a conductor contained within the connecting portion 50.

[0081] The connecting portion 50 may include one or more of the first terminal pin connecting portion 51 and the second terminal pin connecting portion 52.

[0082] The first terminal pin connecting portion 51 is connected to the first terminal pin 21 by a wire and may include a first connection portion on one side, and the second terminal pin connecting portion 52 is connected to the second terminal pin 22 by a wire and may include a second connection portion on one side. The first terminal pin connecting portion 51 and the second terminal pin connecting portion 52 can be connected to the side and top surfaces of the jig portion 20. For example, the first terminal pin connecting portion 51 can be connected to a part of the side surface of the jig portion 20, and the second terminal pin connecting portion 52 can be connected to the top surface of the jig portion 20.

[0083] The method for evaluating the safety of a secondary battery according to the present invention includes the steps of: placing and supporting the cell on a mounting portion and a plate located on one side of the mounting portion; bringing one side of the cell into contact with the terminal pins of the jig portion (S1); charging and discharging the cell (S2); and evaluating the safety of the cell (S3).

[0084] Step (S1) of bringing one side of the cell into contact with the terminal pins of the jig allows the positive and negative terminals on one side of the cell to come into contact with the first and second pin terminals of the jig. Then, the position of the plate can be adjusted to bring the cell and the terminal pins into contact. In other words, the plate can move up and down along the axial direction of the cell, and when the plate moves upward, the cell and the jig come into contact, and when the plate moves downward, the cell and the jig come apart. Here, "up" may mean the direction in which the jig is positioned along the axial direction of the cell.

[0085] Step S2 involves electrically connecting the jig and the charge / discharge device and applying current to the cell. Step S2 may also include step S2-1, which involves discharging flame and heat to the outside. The cell may experience thermal runaway and generate flame after multiple charge / discharge cycles, but in this case, the flame and heat can be discharged to the outside.

[0086] Step S3, which evaluates the safety of the cell, involves evaluating the internal temperature of the cell, the degree of cell expansion, and the degree of decrease in cell efficiency after the cell has been charged and discharged multiple times.

[0087] Although preferred embodiments of the present invention have been described above with reference to the present invention, those skilled in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as described in the following claims. [Examples]

[0088] <Experimental Example 1> To evaluate the safety of secondary batteries, we compared the current applied to the cells during repeated charging and discharging cycles.

[0089] <Comparative Example> In the comparative example, the safety evaluation of a secondary battery was performed using an electrode assembly with welded electrode tabs. The negative and positive electrode tabs were electrically connected by contacting the negative and positive terminal pins of a jig for evaluating the safety of the secondary battery, respectively, and then the battery was repeatedly charged and discharged.

[0090] <Examples> An electrode assembly without electrode tabs, with internal terminals in contact at the top and bottom, was placed in a can. After sealing the can with external terminals, charging and discharging were repeatedly performed using a safety evaluation jig for secondary batteries. The negative and positive terminals of the external terminals were in contact with the negative and positive terminal pins of the safety evaluation jig, and current was applied.

[0091] Figure 5(a) is a photograph of the comparative example set up in a jig for evaluating the safety of a secondary battery, Figure 5(b) is a photograph of the embodiment set up in a jig for evaluating the safety of a secondary battery, Figure 6(a) is a graph showing the applied current measured over time for the comparative example, and Figure 6(b) is a graph showing the applied current measured over time for the embodiment.

[0092] The electrode assemblies of the comparative example and the example can have the same capacity and size. As the capacity and size of the secondary battery increase, it is necessary to adjust the size of the tabs, such as the thickness, material, and length of the tabs.

[0093] Referring to Figure 6(a), it can be seen that in the comparative example, the applied current increases to the maximum current limit of the device in a short time. This is because the tab, which is not suitable for large-capacity secondary batteries, is welded, resulting in a large applied current, which can cause the tab to disconnect due to overheating.

[0094] Referring to Figure 6(b), in this embodiment, although the applied current increases, it does not rise to the upper limit current of the device, and by using an electrode assembly with a structure that does not have electrode tabs, problems such as the electrode tabs breaking or the weldability decreasing do not occur.

[0095] <Experimental Example 2> One of several cells was ignited, and the presence or absence of chain ignition and side rupture in adjacent cells was measured depending on the experimental environment and the outlet gap. The safety evaluation jig for secondary batteries used in this experiment was the safety evaluation jig for secondary batteries according to the present invention, with the auxiliary plate located separately from the main plate.

[0096] <Comparative Example 1> Comparative Example 1 involved placing six cells on a safety evaluation jig for secondary batteries and measuring the presence or absence of chain ignition and side rupture using a safety evaluation jig for secondary batteries with a distance of 1 mm between the plate and the auxiliary plate (discharge gap). In Comparative Example 1, a cooling fluid was introduced into the safety evaluation jig for secondary batteries to maintain the internal temperature of the jig at 20 degrees Celsius.

[0097] <Comparative Example 2> Comparative Example 2 involved placing six cells on a safety evaluation jig for secondary batteries, and measuring the presence or absence of chain ignition and side rupture using a safety evaluation jig for secondary batteries in which the distance between the plate and the auxiliary plate was 1 mm. In Comparative Example 2, the heat of ignition was discharged to the outside through the ignition outlet and outlet gap, making the internal temperature of the safety evaluation jig the same as the external temperature.

[0098] <Examples> Six cells were placed on a safety evaluation jig for secondary batteries, and the presence or absence of chain ignition and lateral rupture was measured using a safety evaluation jig for secondary batteries without an auxiliary plate.

[0099] [Table 1]

[0100] Referring to Table 1, it can be seen that in Comparative Examples 1 and 2, chain ignition occurs when the outlet gap is 1 mm, regardless of the experimental environment. In Comparative Example 1, in addition to the internal temperature of the jig (20°C), ignition heat is generated inside the jig, causing chain ignition and lateral rupture of adjacent cells.

[0101] Comparative Example 2 shows that while ignition heat was released to the ignition outlet and outlet gap without temperature maintenance, and no lateral rupture of the cell occurred, the rate of ignition heat release was slow, resulting in chain ignition.

[0102] Here, lateral rupture means that the side of an adjacent cell ruptures due to the ignition of a cell.

[0103] Examples 1 and 2 demonstrate that when the exhaust port gap is 5 mm or more and the plate includes an ignition port, the heat of ignition is effectively dissipated, the flame duration is short, and therefore, the heat emitted by the ignited cell does not affect adjacent cells, thus preventing chain ignition and lateral rupture. [Explanation of symbols]

[0104] 100 ···Jig for safety evaluation of secondary batteries 10 ··· Mounting section 20 ···Jig section 21 ···First terminal pin 22 ···Second terminal pin 30 ···plate 31...Ignition outlet 40 ···Plate Control Unit 50...Connection part 51...1st terminal connection part 52...Second terminal connection part 200...cells, secondary batteries 1...electrode assembly 2 cans 2a ···Beading section 2b ···Crimping section 3 ···Bent 3a ···Bent Notch 4 ···First current collector plate 4b...1st electrode terminal 5a ···Second current collector plate 5b...Second electrode terminal 5c ··· Second terminal gasket C ···Core section G ···Gasket S ···Insulator

Claims

1. The jig section, A plate positioned opposite the jig section, A jig for safety evaluation of cylindrical secondary batteries, including, The jig portion includes the main body, The main body is provided with a first terminal pin and a second terminal pin, The main body is provided with at least one of the first terminal pin and the second terminal pin so as to be separable / connectable. The first terminal pin and the second terminal pin are configured to contact the external terminals of the cylindrical secondary battery. The second terminal pin is provided around the first terminal pin, The cylindrical secondary battery includes an electrode assembly in which a separator and electrodes are wound, a can that houses the electrode assembly and has an opening on one side and a through hole on the other side, a vent connected to the opening, and a second electrode terminal connected to the through hole. Either the first terminal pin or the second terminal pin has a smaller diameter than or the same diameter as the second electrode terminal. The plate has a support surface for supporting the cylindrical secondary battery, The support surface of the plate is provided so as to face the first terminal pin and the second terminal pin of the jig portion. A safety evaluation jig for a cylindrical secondary battery, wherein the plate includes an ignition outlet that penetrates the plate to discharge flames and heat generated in the cylindrical secondary battery supported by the support surface of the plate to the outside of the safety evaluation jig.

2. The jig for evaluating the safety of a cylindrical secondary battery according to claim 1, wherein the first terminal pin and the second terminal pin are in contact with the positive terminal portion and the negative terminal portion of the cylindrical secondary battery.

3. A safety evaluation jig for a cylindrical secondary battery according to claim 1, wherein one or both of the first terminal pin and the second terminal pin are separated and connected to the main body by a screw structure.

4. A jig for evaluating the safety of a cylindrical secondary battery according to claim 1, further comprising a plate control unit for adjusting the position of the plate, wherein the cylindrical secondary battery supported by the support surface of the plate is brought into contact with or separated from the jig by the plate control unit.

5. A jig for evaluating the safety of a cylindrical secondary battery according to claim 1, further comprising a safety evaluation device for evaluating the safety of the cylindrical secondary battery and a connecting portion for electrically connecting the cylindrical secondary battery via the jig portion, which is connected to the jig portion on the opposite side from the plate portion.

6. The jig for evaluating the safety of a cylindrical secondary battery according to claim 5, wherein the connecting portion includes one or both of a first terminal pin connecting portion electrically connected to the first terminal pin of the jig portion and a second terminal pin connecting portion electrically connected to the second terminal pin of the jig portion.

7. A jig for evaluating the safety of a cylindrical secondary battery according to claim 1, comprising a plurality of the aforementioned plates.

8. The jig for evaluating the safety of a cylindrical secondary battery according to claim 1, further comprising a mounting portion located between the first terminal pin and the second terminal pin of the jig portion and the support surface of the plate, wherein the mounting portion contacts at least a portion of the cylindrical secondary battery to support the cylindrical secondary battery.

9. The mounting portion supports the cylindrical secondary battery by contacting at least a portion of the side surface of the cylindrical secondary battery, as described in claim 8, for safety evaluation of a cylindrical secondary battery.

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