Battery cell quality inspection apparatus and battery cell quality inspection method using the same

Abstract

This disclosure relates to a battery cell quality inspection apparatus for measuring the presence or absence of cracks inside a battery cell and a battery cell quality inspection method using the same. The battery cell quality inspection apparatus of this disclosure includes a pressurized chamber for housing a battery cell, at least one pressurized unit coupled to the pressurized chamber for increasing the internal pressure of the pressurized chamber, and a measuring instrument for measuring the insulation resistance of a battery cell housed inside the pressurized chamber, characterized in that the pressure inside the pressurized chamber is increased to cause the battery cell to contract.

Description

Technical Field

[0001] The present disclosure relates to a battery cell quality inspection device capable of determining the presence or absence of fine cracks inside a battery cell, and a method for inspecting the quality of a battery cell using the same.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0039851 filed on March 22, 2024, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

Background Art

[0003] Rechargeable secondary batteries have been presented as a solution to solve air pollution caused by existing gasoline vehicles, diesel vehicles, etc. using fossil fuels, including electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, etc., and are attracting attention as a power source for devices that require high power and large capacity.

[0004] Typically, in terms of the shape of the battery, there is a high demand for rectangular 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, there is a high demand for lithium secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.

[0005] Such secondary batteries may be classified according to the structure of the electrode assembly having a positive electrode / separator / negative electrode structure. Typically, a jelly roll electrode (winding type) electrode assembly having a structure in which a long sheet-shaped positive electrode and a negative electrode are wound with a separator interposed therebetween, a stack type (lamination type) electrode assembly in which a large number of positive electrodes and negative electrodes cut out in a predetermined size unit are sequentially laminated with a separator interposed therebetween, a stack / folding type electrode assembly having a structure in which a bicell or a full cell in which a positive electrode and a negative electrode in a predetermined unit are laminated with a separator interposed therebetween is wound, etc. may be mentioned.

[0006] Rechargeable batteries have a structure in which an electrode assembly consisting of a positive electrode, a negative electrode, and a separator membrane interposed between them, along with an electrolyte, is housed together in a battery case. As they are devices based on electrochemical reactions, they are inevitably sensitive to environmental factors. Furthermore, because they are manufactured through a series of processes in which small components are precisely mounted and connected in a limited space, product quality can deteriorate due to factors such as errors in some equipment or the inexperience of some workers. In addition, in the manufacturing process of rechargeable batteries using mass production systems, even small defects in the process can lead to serious defects.

[0007] Therefore, thorough inspection of secondary batteries must be carried out at each manufacturing step and / or after the production of the finished product. Such inspection is important in terms of quality control, as it is one of the most important aspects of secondary battery production, confirming whether or not they provide the desired performance and stability. Here, quality control means accurately determining whether secondary batteries have proper charge and discharge performance, producing good products, and sorting out defective products. By properly implementing such quality control, high-quality secondary batteries can be produced.

[0008] Microscopic cracks inside the battery case are one of the various causes of failure in rechargeable batteries. Electrolyte can penetrate these microscopic cracks, and this penetration can destroy the insulation of the battery case, creating a risk of current leakage.

[0009] Conventionally, to inspect for the microcracks described above, measuring instruments were connected to the battery case and electrode leads to observe the leakage current. However, this method not only increases the inspection time, but also has the problem that the electrolyte does not penetrate the microcracks properly, making it difficult to observe the leakage current even when microcracks are present.

[0010] To solve the problems described above, a method was introduced in which a complete rechargeable battery is physically pressurized to artificially penetrate the electrolyte into microcracks and measure the leakage current. However, since pressurization by physical contact as described above could cause additional damage to the rechargeable battery case or the internal electrode assembly, existing inspection methods using physical pressurization are generally avoided. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Korean Published Patent No. 10-2023-0173521 [Overview of the project] [Problems that the invention aims to solve]

[0012] Therefore, this disclosure was created to solve the above-mentioned problems and aims to provide an inspection device and inspection method that can confirm the presence or absence of internal cracks without damaging the battery cell.

[0013] Other purposes and advantages of this disclosure can be understood from the description below and will be more clearly seen from the embodiments of this disclosure. Furthermore, it will be readily apparent that the purposes and advantages of this disclosure can be achieved by the means and combinations set forth in the claims. [Means for solving the problem]

[0014] According to this disclosure, a battery cell quality inspection device is provided that measures whether or not cracks have occurred inside the battery cell.

[0015] The above-described battery cell quality inspection apparatus includes a pressurized chamber that houses battery cells, at least one pressurized unit coupled to the pressurized chamber and increasing the internal pressure of the pressurized chamber, and a measuring instrument for measuring the insulation resistance of the battery cells housed inside the pressurized chamber, characterized in that the pressure inside the pressurized chamber is increased to cause the battery cells to contract.

[0016] The above-mentioned pressurizing unit can increase the pressure by injecting gas into the pressurizing chamber.

[0017] The above-mentioned pressurized chamber may have a sealed structure that prevents gas from entering or leaving the outside.

[0018] The above pressurizing unit can be used to pressurize the internal pressure of the pressurizing chamber to 3 bar to 30 bar.

[0019] The above-mentioned pressurized chamber may have sufficient strength to withstand the pressure applied by the pressurized unit without deforming.

[0020] The above measuring instrument can be electrically connected to a battery cell housed inside the pressurized chamber to measure its insulation resistance.

[0021] The above-mentioned battery cell may include an electrode assembly in which electrodes and separator membranes are alternately stacked, a pair of electrode leads electrically connected to the electrodes of the electrode assembly, a battery case surrounding the electrode assembly such that the electrode leads are led out to the outside, and an electrolyte filled inside the battery case together with the electrode assembly.

[0022] The above measuring instrument can electrically connect the battery case of the battery cell and one of the electrode leads to apply a voltage and measure the insulation resistance over time.

[0023] According to this disclosure, a battery cell quality inspection method is provided for measuring the presence or absence of cracks in a battery cell using the battery cell quality inspection apparatus of this disclosure.

[0024] The above battery cell quality inspection method includes a first step of inserting a battery cell into a pressure chamber equipped with a pressurizing unit, a second step of connecting a measuring instrument to the battery cell, and a third step of increasing the internal pressure of the pressure chamber via the pressurizing unit, and is characterized by increasing the internal pressure of the pressure chamber and measuring the insulation resistance of the battery cell via the measuring instrument.

[0025] The above pressurizing unit can pressurize so that the internal pressure of the pressure chamber becomes 3 bar to 30 bar.

[0026] The above insulation resistance can be obtained by the following formula 1.

[0027]

Equation

Advantages of the Invention

[0028] According to the present disclosure, it is possible to effectively confirm the presence or absence of crack generation inside the battery cell without damaging the battery cell to be inspected.

Brief Description of the Drawings

[0029] [Figure 1] It is a schematic diagram simply showing the battery cell quality inspection device of the present disclosure. [Figure 2] It is a plan view and a side view of a battery cell used for inspection. [Figure 3] It is a partial cross-sectional view of the battery cell in FIG. 2. [Figure 4] It is a schematic diagram simply showing the measuring instrument of the present disclosure. [Figure 5] It is a schematic diagram showing a modified example of the battery cell quality inspection device of the present disclosure. [Figure 6] It is a diagram schematically showing the process of the battery cell quality inspection method of the present disclosure. [Figure 7] It is a cross-sectional view schematically showing the deformation inside the battery cell due to pressurization.

Modes for Carrying Out the Invention

[0030] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings. As a premise, terms and words used herein and in the claims should not be construed to be limited to their general or dictionary meanings, but rather to mean and define terms in accordance with the technical spirit of this disclosure, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their own inventions.

[0031] Therefore, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the disclosure and do not represent the entire technical concept of the disclosure. As a result, there may be a variety of equivalents and modifications that can be substituted for them at the time of filing.

[0032] Furthermore, if it is determined that a specific description of a relevant publicly known configuration or function in this disclosure would obscure the gist of this disclosure, such detailed description will be omitted.

[0033] Since embodiments of this disclosure are provided to explain the disclosure more fully to a person of ordinary skill, the shapes and sizes of components in the drawings may be exaggerated, omitted, or shown schematically for the sake of clarity. Accordingly, the sizes and proportions of each component do not fully reflect their actual sizes and proportions.

[0034] This disclosure relates to a battery cell quality inspection device capable of determining whether or not microcracks have occurred inside a battery cell, and a method for inspecting the quality of a battery cell using the same.

[0035] Figures 1 to 5 relate to the battery cell quality inspection apparatus of this disclosure, and Figures 6 to 7 relate to the battery cell quality inspection method of this disclosure.

[0036] Specific embodiments of the battery cell quality inspection apparatus and battery cell quality inspection method of this disclosure will be described in detail below with reference to the attached drawings. For reference, the forward / backward and up / down / left / right directions used in the following description to specify relative positions are for the purpose of aiding the understanding of the invention, and unless otherwise defined, the directions shown in the drawings shall be used as the reference.

[0037] <Battery cell quality inspection device 200> The battery cell quality inspection device 200 of this disclosure measures whether or not cracks C have formed inside the battery cell 100.

[0038] Figure 1 is a schematic diagram briefly showing the battery cell quality inspection apparatus 200 of this disclosure; Figure 2 is a plan view and a side view of the battery cell 100 used for inspection; and Figure 3 is a cross-sectional view of a part of the battery cell 100 in Figure 2.

[0039] The battery cell 100 to be measured in this disclosure has a pouch type with electrode leads 130 led out to the outside.

[0040] Specifically, the battery cell 100 is a pouch-type secondary battery comprising an electrode assembly 110 in which electrodes and a separator membrane are alternately stacked, a pair of electrode leads 130 electrically connected to the electrodes of the electrode assembly 110, a battery case 120 surrounding the electrode assembly 110 such that the electrode leads 130 are led out to the outside, and an electrolyte 140 filled inside the battery case 120 together with the electrode assembly 110.

[0041] The above electrode has an electrode tab 111 formed on one side, and the surface is coated with an active material.

[0042] Specifically, the electrode may be a positive electrode in which a slurry of positive electrode active material, binder resin, conductive material, and other additives is applied to at least one surface of the current collector, or a negative electrode in which a slurry of negative electrode active material, binder resin, conductive material, and other additives is applied to at least one surface of the current collector. Therefore, the electrode assembly 110 is constructed by alternately stacking a positive electrode, a separator membrane, and a negative electrode.

[0043] As shown in Figure 2, the electrode tab 111 is electrically connected by having multiple layers coupled to a single electrode lead 130.

[0044] Of the pair of electrode leads 130 included in the battery cell 100, one is a positive electrode lead electrically connected to the positive electrode of the electrode assembly 110, and the other is a negative electrode lead electrically connected to the negative electrode of the electrode assembly 110.

[0045] The above-mentioned separation membrane can be made from a conventional porous polymer film used in lithium-ion batteries.

[0046] The battery case 120 described above is made of aluminum material that maintains mechanical strength and prevents the penetration of moisture and oxygen, and the inner surface may be coated with a case film 160 made of a material such as polyolefin.

[0047] The pair of electrode leads 130 can be led out to one side of the battery case 120, or, as shown in Figure 2, they can be led out to both sides of the battery case 120, respectively.

[0048] As shown in Figure 3, an insulating film 150 made of an insulating material is interposed between the contact point between the electrode lead 130 and the battery case 120, and the battery case 120 can be insulated by the insulating film 150.

[0049] Although not shown in Figure 3, the battery case 120 is filled with electrolyte 140 along with the electrode assembly 110.

[0050] The battery case 120 is sealed by welding or the like to prevent the filled electrolyte 140 and the gas generated in the electrode assembly 110 from leaking to the outside.

[0051] The pressurized chamber 210 provides a space in which the battery cell 100 to be measured is installed.

[0052] Preferably, the pressurized chamber 210 has sufficient strength to withstand the increasing pressure without deforming when high pressure is applied to the battery cell 100 housed inside it.

[0053] Furthermore, it is preferable that the pressurized chamber 210 has a sealed structure to prevent gas from entering or leaving the outside.

[0054] Figure 4 is a schematic diagram that briefly illustrates the measuring instrument 230 of this disclosure.

[0055] The measuring instrument 230 measures the insulation resistance of the battery cell 100 housed inside the pressurized chamber 210. More specifically, the measuring instrument 230 is electrically connected to the battery cell 100 housed inside the pressurized chamber 210 to measure its insulation resistance.

[0056] The battery cell quality inspection apparatus 200 of this disclosure can measure the insulation resistance of the battery cell 100 by inspecting the current of the battery cell 100 using the measuring instrument 230.

[0057] The measuring instrument 230 includes a power supply unit 232, a leakage current meter, and a wire 231 connecting the power supply unit 232 and the leakage current meter to the battery cell 100.

[0058] As shown in Figures 1 and 4, the measuring instrument 230 is electrically connected to the battery case 120 of the battery cell 100 and one of the electrode leads 130 using a wire 231. By being electrically connected to the battery case 120 and electrode lead 130 as described above, the measuring instrument 230 measures the insulation resistance of the battery cell 100 over time.

[0059] The power supply unit 232 applies voltage to the battery cell 100, and the current measurement unit 233 measures the leakage current.

[0060] The insulation resistance of the above battery cell 100 can be calculated using the following formula 1.

[0061]

number

[0062] The pressurizing unit 220 is connected to the pressurizing chamber 210 and plays a role in increasing the internal pressure of the pressurizing chamber 210.

[0063] In other words, the battery cell quality inspection apparatus 200 of this disclosure increases the internal pressure of the pressurizing chamber 210 with the pressurizing unit 220 to shrink the battery cell 100, and measures the insulation resistance of the battery cell 100 using the measuring instrument 230 while the battery cell 100 is shrinking.

[0064] Specifically, the pressurizing unit 220 increases the pressure by injecting gas into the pressurizing chamber 210. Therefore, the battery cell 100 housed inside the pressurizing chamber 210 may partially contract due to the increasing pressure.

[0065] Preferably, the pressurizing unit 220 pressurizes the internal pressure of the pressurizing chamber 210 to 3 bar to 30 bar. If the pressure is less than 3 bar, the battery cell 100 may not be sufficiently pressurized, and if it exceeds 30 bar, there is a risk of damage to the battery cell 100.

[0066] Figure 5 is a schematic diagram showing a modified example of the battery cell quality inspection apparatus 200 of this disclosure.

[0067] The battery cell quality inspection apparatus 200 of this disclosure may use at least one or more pressurizing units 220. For example, two pressurizing units 220 may be used, as shown in Figure 5.

[0068] When multiple pressurizing units 220 are provided in this manner, the time required to reach the desired pressure can be effectively shortened.

[0069] <Battery Cell Quality Inspection Method for 100 Cells> Figure 6 is a schematic diagram illustrating the process of the battery cell 100 quality inspection method of this disclosure, and Figure 7 is a schematic cross-sectional view illustrating the deformation inside the battery cell 100 due to pressurization.

[0070] The quality inspection of the battery cell 100 of this disclosure is carried out using the battery cell quality inspection device 200 of this disclosure.

[0071] The quality inspection of the battery cell 100 described herein may be carried out in several steps, as shown in Figure 6.

[0072] Step 1 (S1) This step involves inserting the battery cell 100 into the pressurized chamber 210, which is equipped with a pressurizing unit 220.

[0073] The battery cell 100 is mounted inside a sealable pressurized chamber 210, as shown in Figure 6.

[0074] Step 2 (S2) This step involves connecting the measuring instrument 230 to the battery cell 100.

[0075] To test the insulation resistance of the battery cell 100 installed inside the pressurized chamber 210, the measuring instrument 230 is electrically connected to the electrode leads 130 of the battery cell 100 and the battery case 120. For example, the measuring instrument 230 can be connected to the negative electrode lead of the battery cell 100 and the battery case 120 via conductors 231, respectively.

[0076] The measuring instrument 230 applies voltage to the battery cell 100 and measures whether or not leakage current occurs.

[0077] The applied voltage is between 1V and 2000V.

[0078] Step 3 (S3) This step involves increasing the internal pressure of the pressurizing chamber 210 via the pressurizing unit 220.

[0079] The battery cell 100 quality inspection method of this disclosure is characterized by increasing the internal pressure of the pressurized chamber 210 and measuring the insulation resistance of the battery cell 100 via the measuring instrument 230.

[0080] Therefore, once the measuring instrument 230 is connected and ready to measure the insulation resistance of the battery cell 100, the pressurizing unit 220 is activated to increase the pressure inside the pressurizing chamber 210.

[0081] The internal pressure of the pressurizing chamber 210 is preferably 3 bar to 30 bar. If the internal pressure of the pressurizing chamber 210 is less than 3 bar, it will not be possible to transmit sufficient pressure to the battery cell 100, and if it exceeds 30 bar, there is a risk of damage to the battery cell 100.

[0082] The battery cell 100 quality inspection in this disclosure involves adjusting the internal pressure of the pressurizing chamber 210 within the above pressure range, observing whether or not leakage current occurs in the battery cell 100, and determining the insulation resistance of the battery cell 100 based on this.

[0083] The above insulation resistance can be calculated using the following formula 1.

[0084]

number

[0085] The power supply unit 232 included in the measuring instrument 230 applies voltage to the battery cell 100, and the current measuring unit 233 checks for leakage current.

[0086] In the case of a normal battery cell 100, it is considered that the battery case 120 maintains an electrically insulated state from the electrode assembly 110 or electrode lead 130, and therefore, no leakage current is expected to be observed through the measuring instrument 230.

[0087] Conversely, if a battery cell 100 has a fine crack C inside the battery case 120, it is thought that the electrolyte 140 will penetrate the fine crack C due to external pressure, destroying the insulation state. Therefore, leakage current will be observed through the measuring instrument 230.

[0088] As shown in Figure 7 above, a portion of the battery case 120 is pressed by pressure, and this pressing causes the electrolyte 140 to penetrate into the microscopic cracks C inside the battery case 120. Therefore, the battery cell 100 into which the electrolyte 140 has penetrated can be seen as having its internal insulation destroyed, which may result in a low voltage due to an internal short circuit or a decrease in performance.

[0089] The present disclosure has been described in more detail above with reference to the drawings and embodiments. However, the configurations described in the drawings or embodiments described herein represent only one embodiment of the present disclosure and do not represent the entire technical concept of the present disclosure. Therefore, there may be various equivalents and modifications that can be substituted for them at the time of filing. [Explanation of symbols]

[0090] 100: Battery cell 110: Electrode assembly 111: Electrode Tab 120: Battery case 130: Electrode Leads 140: Electrolyte 150: Insulating film 160: Case film 200: Battery cell quality inspection device 210: Pressurized Chamber 220: Pressurization Unit 230: Measuring Instruments 231: Conductor 232: Power supply unit 233: Current measurement unit C: Crack S1: Step 1 S2: Step 2 S3: Step 3

Claims

1. A battery cell quality inspection device that measures whether or not cracks have occurred inside the battery cell, A pressurized chamber containing battery cells inside, A pressurizing unit coupled to the pressurizing chamber and increasing the internal pressure of the pressurizing chamber, The instrument includes a measuring instrument for measuring the insulation resistance of a battery cell housed inside the pressurized chamber, A battery cell quality inspection device that increases the pressure inside the pressurized chamber to shrink the battery cell.

2. The battery cell quality inspection apparatus according to claim 1, wherein the pressurizing unit increases the pressure by injecting gas into the pressurizing chamber.

3. The battery cell quality inspection apparatus according to claim 1, wherein the pressurized chamber has a sealed structure that prevents gas from entering or leaving the outside.

4. The battery cell quality inspection apparatus according to claim 1, wherein the pressurizing unit pressurizes the internal pressure of the pressurizing chamber to 3 bar to 30 bar.

5. The battery cell quality inspection apparatus according to claim 1, wherein the pressurizing chamber has strength that does not deform under the pressure applied by the pressurizing unit.

6. The battery cell quality inspection apparatus according to claim 1, wherein the measuring instrument is electrically connected to a battery cell housed inside the pressurized chamber to measure its insulation resistance.

7. The battery cell quality inspection apparatus according to claim 1, wherein the battery cell is a pouch-type secondary battery comprising an electrode assembly in which electrodes and a separator membrane are alternately stacked, a pair of electrode leads electrically connected to the electrodes of the electrode assembly, a battery case surrounding the electrode assembly such that the electrode leads are led out to the outside, and an electrolyte filled inside the battery case together with the electrode assembly.

8. The battery cell quality inspection apparatus according to claim 7, wherein the measuring instrument is electrically connected to the battery case of the battery cell and one of the electrode leads, a voltage is applied, and the insulation resistance over time is measured.

9. A battery cell quality inspection method for measuring the presence or absence of cracks in a battery cell using the battery cell quality inspection apparatus described in claim 1, The first step is to insert a battery cell into a pressurized chamber equipped with a pressurizing unit, The second step is to connect a measuring instrument to the aforementioned battery cell, The third step includes increasing the internal pressure of the pressurizing chamber via the pressurizing unit, A battery cell quality inspection method comprising increasing the internal pressure of the pressurized chamber and measuring the insulation resistance of the battery cell via the measuring instrument.

10. The battery cell quality inspection method according to claim 9, wherein the pressurizing unit pressurizes the internal pressure of the pressurizing chamber to 3 bar to 30 bar.

11. The insulation resistance is determined by the following formula 1, as described in claim 9, for the battery cell quality inspection method. [Math 1]

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