Device and method for causing a short circuit inside the battery

Abstract

The present invention relates to a battery internal short circuit inducing device and method comprising a separator cover that covers the opening of the separator so as to be accurately controlled during a battery internal short circuit test to obtain a constant short circuit inducing effect.

Description

Technology Field

[0001] The present invention relates to a device and method for inducing an internal short circuit in a battery. More specifically, the invention relates to a device and method for inducing an internal short circuit in a battery, comprising a separator cover that covers a separator opening to be accurately controlled during an internal short circuit test to obtain a constant short circuit inducing effect. Background Technology

[0003] As the price of energy sources rises due to the depletion of fossil fuels and concerns about environmental pollution intensify, the demand for eco-friendly alternative energy sources is becoming an indispensable factor for future life; in particular, with the technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly rising.

[0004] In terms of battery shape, there is high demand for prismatic and pouch-type rechargeable batteries, which can be applied to products such as mobile phones due to their thin thickness; in terms of materials, there is high demand for lithium-ion batteries and lithium-ion polymer batteries, which offer high energy density, discharge voltage, and output stability.

[0005] Generally, a secondary battery is manufactured by forming an electrode assembly by coating an electrode composite containing an electrode active material onto the surface of a current collector to form a positive electrode and a negative electrode, interposing a separator between them, and then mounting the assembly inside a pouch-type case made of a cylindrical or prismatic metal can or an aluminum laminate sheet, and mainly injecting or impregnating a liquid electrolyte into the electrode assembly or using a solid electrolyte.

[0006] In addition, secondary batteries are classified according to the structure of the electrode assembly comprising the positive electrode, separator, and negative electrode. Representative examples include a jelly-roll (wound type) electrode assembly in which long sheet-type positive and negative electrodes are wound with a separator interposed; a stack type (stacked type) electrode assembly in which multiple positive and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed; and a stack / folding type electrode assembly in which bi-cells or full cells, formed by stacking positive and negative electrodes of a predetermined unit with a separator interposed, are wound with a separator sheet.

[0007] Meanwhile, electrodes generate current through the exchange of ions, and the positive and negative electrodes forming the electrodes are structured such that an electrode active material is coated onto a metal electrode current collector.

[0008] Generally, the cathode consists of a structure in which a carbon-based active material is coated on an electrode plate made of copper or aluminum, and the anode consists of a structure in which an active material composed of LiCoO2, LiMnO2, LiNiO2, etc. is coated on an electrode plate made of aluminum.

[0009] In order to manufacture the positive or negative electrode in this way, an electrode mixture containing an electrode active material is applied to an electrode current collector consisting of a long metal sheet in one direction.

[0010] The separator is located between the positive and negative electrodes of the battery to provide insulation and maintain the electrolyte, thereby providing a pathway for ion conduction.

[0011] These secondary batteries are rechargeable batteries manufactured using materials capable of repeating multiple oxidation-reduction processes between current and the material; when a reduction reaction is performed on the material by the current, the power is charged, and when an oxidation reaction is performed on the material, the power is discharged, and electricity is generated as this charging and discharging cycle is repeatedly performed.

[0012] While lithium secondary batteries have excellent electrical characteristics, they have the problem of low safety. For example, when lithium secondary batteries are subjected to abnormal operating conditions such as overcharging, over-discharging, exposure to high temperatures, or electrical short circuits, decomposition reactions of battery components such as active materials and electrolytes are induced, generating heat and gas. The resulting high temperature and high pressure conditions further accelerate these decomposition reactions, eventually leading to ignition or explosion.

[0013] Furthermore, it is crucial to ensure safety even in the event of an internal short circuit in the battery; to achieve this, it is essential to properly evaluate the battery's safety in the event of such an internal short circuit. As a safety criterion for batteries such as lithium-ion rechargeable batteries, battery evaluation tests assessing heat generation behavior during an internal short circuit have been established, for example, through the UL standard for lithium batteries (UL 1642) and guidelines from the Battery Industry Association (SBA G1101-1997 Guidelines for Safety Evaluation Criteria of Lithium Rechargeable Batteries). Conventionally, methods used to induce an internal short circuit involved inserting a heating element to generate internal heat, and the internal separator

[0014] There were methods involving pre-drilling holes and chemically treating them to melt at a specific temperature, inserting a metal material of a specific shape and applying external force to tear the separator and induce an internal short circuit, and creating holes in the separator and applying pressure. However, the first method resulted in a difference in form between the actual product and the device due to internal heating elements and external heat sources; the second method required deformation of the separator and chemical treatment of damaged parts, which could lead to differences in characteristics compared to existing products and prevent the desired reaction from occurring due to side reactions caused by internal chemical processes. The third method, which used a battery internal short circuit induction device by creating holes in the separator and applying pressure, presented a problem where it was difficult to obtain consistent experimental results because the internal short circuit resistance did not occur immediately and varied over time.

[0015] Accordingly, there is no technology disclosed in a battery internal short circuit induction device and method comprising a separator cover covering a separator with an opening formed therein to derive a consistent and constant internal short circuit resistance when inducing a battery internal short circuit. Prior art literature

[0017] Korean Published Patent Application No. 2020-0053782 Korean Published Patent Application No. 2021-0077512 The problem to be solved

[0018] The present invention aims to solve the above-mentioned problems by providing a battery internal short circuit inducing device and method comprising a separator cover that covers the separator opening to obtain a constant short circuit inducing effect by accurately controlling the battery internal short circuit during an experiment. means of solving the problem

[0020] A battery internal short circuit inducing device of the present invention for achieving such an objective comprises: an electrode assembly including a positive electrode (110), a negative electrode (120), and a separator (130) interposed between the positive electrode and the negative electrode; a movable pressurizing unit (150) located above the electrode assembly; a supporting unit (160) located below the electrode assembly and supporting the electrode assembly in a fixed position; and a pulling unit (170) for pulling to remove the separator cover from the electrode assembly; wherein the separator may be a battery internal short circuit inducing device having one or more openings (131) formed therein.

[0021] In addition, a conductive material (132) may be interposed in the opening.

[0022] In addition, the average diameter of the opening may be 10 μm to 2 mm.

[0023] Additionally, it may include a separator cover (140) interposed between the separator and the anode and / or cathode.

[0024] In addition, the separator cover can completely cover the opening in contact with the electrode.

[0025] In addition, the conductive material may be a metal piece having the same shape and size as the planar shape and size of the opening, or a metal powder that can be filled into the opening.

[0026] In addition, the present invention may be a method for causing an internal short circuit in a battery, comprising the steps of: preparing an electrode assembly including a separator interposed between an anode and a cathode and a separator cover interposed between the separator and the anode; placing the electrode assembly between a support unit and a pressurizing unit; pulling the separator cover using a pulling unit; and pressing the electrode assembly with the pressurizing unit, wherein the separator has at least one opening formed therein and a conductive material interposed in the opening.

[0027] In addition, the conductive material may be a metal piece or metal powder having the same shape and size as the planar shape and size of the opening.

[0028] In addition, the pulling unit can remove the stacked separator cover in a direction orthogonal to the stacking direction when a short circuit is caused inside the battery. Effects of the invention

[0030] As explained above, the battery internal short-circuit inducing device and method have the effect of ensuring that metal pieces make precise contact when the separator is removed and pressurized.

[0031] In addition, when a conductive material in the form of nickel powder is inserted into the opening, it is easy to fill the separator opening in powder form, and due to the high electrical conductivity, it has an advantageous effect for simulating internal short-circuit resistance.

[0032] In addition, it is possible to detect a short circuit between electrodes at a specific SOC, and it has the effect of causing a battery short circuit in an actual operating state without disassembling the battery.

[0033] In addition, it is possible to induce an internal short circuit not only in the initial state but also after degradation, which has the effect of efficiently performing the stability evaluation of the battery. Brief explanation of the drawing

[0035] FIG. 1 is a cross-sectional view showing a separator cover interposed on one surface of an open separator according to an embodiment of the battery internal short-circuit inducing device of the present invention. FIG. 2 is a cross-sectional view showing a separator cover covering one side of a conductive material filled in an opening of a separator according to an embodiment of the battery internal short-circuit inducing device of the present invention. FIG. 3 is a cross-sectional view of a battery internal short circuit induction device including a pressurizing unit, a support unit, and a separator cover pulling unit according to an embodiment of the battery internal short circuit induction device of the present invention. FIG. 4 is an upper drawing showing the change in position of the separator cover according to the operation of the pulling unit according to one embodiment of the battery internal short-circuit induction device of the present invention. Specific details for implementing the invention

[0036] Hereinafter, with reference to the attached drawings, embodiments that enable a person skilled in the art to easily implement the present invention will be described in detail.

[0037] However, in describing the operating principle of a preferred embodiment of the present invention in detail, if it is determined that a specific description of related known functions or configurations could unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0038] In addition, the same reference numerals are used for parts that have similar functions and operations throughout the drawing.

[0039] Throughout the specification, when it is stated that one part is connected to another part, this includes not only cases where they are directly connected, but also cases where they are indirectly connected through an intermediate means.

[0040] Furthermore, including a certain component means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0041] The present invention will be explained in more detail below.

[0042] FIG. 1 is a cross-sectional view showing a separator cover interposed on one surface of an open separator according to an embodiment of the battery internal short-circuit inducing device of the present invention.

[0043] The internal short-circuit test is a safety test designed to evaluate resistance to internal short circuits, simulating a scenario where the positive and negative electrodes short-circuit within the battery. In this test, a fully charged evaluation battery is prepared, an internal short circuit is induced, and the battery's behavior is assessed. Generally, when an internal short circuit occurs, the battery discharges and its voltage decreases; the test is conducted until the voltage drops below a certain level to evaluate the presence of rupture, battery voltage, temperature, and other factors.

[0044] In lithium-ion secondary batteries, oxidation-reduction reactions occur as lithium ions move between the negative and positive electrodes; however, in the case of conventional batteries equipped with internal short-circuit induction devices as described above, the movement of lithium ions is blocked by aluminum and copper plates in the area where the device is installed, resulting in the formation of an unreacted region. Due to this unreacted region, battery performance, such as capacity, is reduced compared to existing batteries, and there were problems where the accuracy of safety evaluations was reduced because it was difficult to accurately simulate the battery's behavior in the event of an internal short circuit.

[0045] An opening capable of inducing an internal short circuit can take various forms, but in terms of adhesive stability and structural stability, it can be a hole, a circle, or can be formed with various shapes.

[0046] The outer periphery of the opening further includes an adhesive layer for adhering to an electrode. The adhesive layer may be formed in the portion of the outer periphery that contacts the separator, and one or more layers may be formed in the opening.

[0047] The above adhesive includes polyvinylidene fluoride (PVDF), silver paste, etc., and there are no special restrictions on the type of chemical substance as long as it is designed to enable current conduction between the internal short-circuit inducing device and the electrode without affecting the properties of the separator and the electrode in which the opening of the internal short-circuit inducing device is formed. In addition, the above chemical substance has an opening

[0048] It is desirable to use a material that does not impede the electrical connection between the opening and the electrode in order to cause an internal short circuit when in contact with the electrode.

[0049] Among the above chemicals, PVDF is a material used as a binder for electrodes and has the advantage of possessing excellent chemical resistance and good mechanical, thermal, and electrical properties, which are advantages of fluoropolymer resins. In addition, silver paste can be used as an adhesive for the internal short-circuit induction device to achieve bonding and electrical connection of the internal short-circuit induction device.

[0050] The outer periphery of the above opening may be in close contact with the electrode and may not form an adhesive layer with the above separator cover.

[0051] A battery internal short-circuit inducing device comprises an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; the separator may be a battery internal short-circuit inducing device having one or more openings formed therein.

[0052] FIG. 2 is a cross-sectional view showing a separator cover covering one side of a conductive material filled in an opening of a separator according to an embodiment of the battery internal short-circuit inducing device of the present invention.

[0053] The above-mentioned battery internal short-circuit inducing device may be configured with a separate separator combined with a perforated separator, a piece of copper metal which is a conductive material, configured inside the battery, a device unit for applying pressure from the outside of the battery, and a removal unit for removing the separator cover.

[0054] The above metal piece may be in the form of a disc or nickel powder.

[0055] In addition, a conductive material may be interposed in the above opening.

[0056] In addition, the average diameter of the opening may be 10 μm to 2 mm.

[0057] If the size of the opening formed in the separator is less than 10㎛, the lithium ion permeability decreases so that a reaction region cannot be sufficiently formed, and if the size of the pore exceeds 2mm, the volume of the separator decreases excessively, and as a result, the structure of the separator is weakened, so the internal short-circuit effect through the opening cannot be sufficiently supported and can be easily damaged by external factors.

[0058] In addition, the average diameter of the opening may be 0.3 to 2 cm, and more preferably 0.3 to 1.5 cm. When the diameter of the opening is within the above range, the structure of the internal short-circuit inducing device is difficult to destroy even when the electrode assembly is subjected to external force, and an internal short circuit can be effectively generated.

[0059] If the diameter of the opening is less than 0.3 cm, the size of the internal short-circuit inducing device is excessively small, so a short circuit occurs in a narrow area, and as a result, the effect of the short circuit may not be sufficient, and if the diameter of the opening exceeds 2 cm, the internal short-circuit inducing device (200) may easily bend or deform and be destroyed as the electrode assembly receives an external force.

[0060] In addition, it may include a separator cover interposed between the separator and the anode and / or cathode.

[0061] The separator cover can be made of the same material as the separator.

[0062] The conductivity of the separator cover can be equal to or lower than that of the separator.

[0063] The thickness of the above-mentioned separator cover may be equal to or smaller than the separator. The thickness may be 10 μm to 500 μm. If the thickness is outside the above range, removing the separator cover may not be easy.

[0064] In addition, the separator cover can completely cover the opening in contact with the electrode.

[0065] Additionally, it may include a movable pressurizing unit located at the upper part of the electrode assembly; a supporting unit located at the lower part of the electrode assembly and supporting the electrode assembly in a fixed position; and a pulling unit for pulling to remove the separator cover from the electrode assembly.

[0066] One embodiment of the pulling unit may be a towing type. A separator cover is connected to one end of the towing unit, and when the towing unit is driven at the time of removal, the separator cover can be pulled and removed.

[0067] One embodiment of the pulling unit may have a removal rod formed on one side of a rotating motor. When the motor is driven at the time of removal, the removal rod formed on one side strikes the separator cover and pulls the separator cover to remove it.

[0068] The above pulling unit may be in the form of a roller.

[0069] In addition, the conductive material may be a metal piece having the same shape and size as the planar shape and size of the opening, or a metal powder that can be filled into the opening.

[0070] The above conductive material may be a metal material that does not react with components such as an electrolyte and has good electrical conductivity, preferably one selected from the group including aluminum, copper, and titanium, and more preferably aluminum or copper.

[0071] FIG. 3 is a cross-sectional view of a battery internal short circuit induction device including a pressurizing unit, a support unit, and a separator cover pulling unit according to an embodiment of the battery internal short circuit induction device of the present invention.

[0072] In addition, the present invention may be a method for causing an internal short circuit in a battery, comprising the steps of: preparing an electrode assembly including a separator interposed between an anode and a cathode and a separator cover interposed between the separator and the anode; placing the electrode assembly between a support unit and a pressurizing unit; pulling the separator cover using a pulling unit; and pressing the electrode assembly with the pressurizing unit, wherein the separator has at least one opening formed therein and a conductive material interposed in the opening.

[0073] In addition, the conductive material may be a metal piece or metal powder having the same shape and size as the planar shape and size of the opening.

[0074] FIG. 4 is an upper drawing showing the change in position of the separator cover according to the operation of the pulling unit according to one embodiment of the battery internal short-circuit induction device of the present invention.

[0075] Figure 4 (a) is a drawing showing a membrane cover covering the opening of the membrane, and (b) is a drawing showing a membrane cover removed from the opening of the membrane by a pulling unit.

[0076] As specific parts of the present invention have been described in detail above, it is obvious to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the invention, and that various changes and modifications are possible within the scope and spirit of the invention, and that such variations and modifications fall within the scope of the appended claims. Explanation of the symbols

[0078] 100: Internal short-circuit induction device 110: Anode 120: Cathode 130: Separator 131: Opening 132: Conductive material 140: Separator cover 150: Pressurization unit 160: Support Unit 170: Pulling unit

Claims

Claim 1 A battery internal short-circuit inducing device comprising: an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a movable pressurizing unit located above the electrode assembly; a support unit located below the electrode assembly and supporting the electrode assembly in a fixed position; and a pulling unit for pulling to remove the separator cover from the electrode assembly, wherein the separator has one or more openings formed therein. Claim 2 A battery internal short-circuit inducing device having a conductive material interposed in the opening in claim 1. Claim 3 A battery internal short-circuit inducing device according to claim 1, wherein the average diameter of the opening is 10 μm to 2 mm. Claim 4 A battery internal short-circuit inducing device comprising, in claim 1, a separator cover interposed between the separator and the positive and / or negative electrode. Claim 5 In paragraph 4, the separator cover is a battery internal short-circuit inducing device that completely covers the opening in contact with the electrode. Claim 6 In paragraph 4, the thickness of the separator cover is thinner than the separator, forming a battery internal short-circuit inducing device. Claim 7 A battery internal short-circuit inducing device, wherein the conductive material is a metal piece having the same shape and size as the planar shape and size of the opening, or a metal powder that can be filled into the opening. Claim 8 A method for causing an internal short circuit in a battery, comprising: a step of preparing an electrode assembly including a separator interposed between an anode and a cathode and a separator cover interposed between the separator and the anode; a step of placing the electrode assembly between a support unit and a pressurizing unit; a step of pulling the separator cover using a pulling unit; and a step of pressing the electrode assembly with the pressurizing unit; wherein the separator has at least one opening formed therein and a conductive material interposed in the opening. Claim 9 A method for causing an internal short circuit in a battery, wherein the conductive material is a metal piece having the same shape and size as the planar shape and size of the opening, or a metal powder that can be filled into the opening. Claim 10 In claim 8, the pulling unit removes the stacked separator cover in a direction perpendicular to the stacking direction when causing an internal short circuit in the battery, in a method for causing an internal short circuit in the battery.

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