Battery cell quality inspection device and method for inspecting quality of battery cell thereby

Abstract

The present invention relates to a battery cell quality inspection device for measuring whether cracks occur inside a battery cell and a method for inspecting the quality of a battery cell thereby. The battery cell quality inspection device of the present invention comprises: a pressurizing chamber for containing a battery cell therein; at least one pressurizing unit coupled to the pressurizing chamber so as to increase the internal pressure of the pressurizing chamber; and a measuring instrument for measuring the insulation resistance of the battery cell contained in the pressurizing chamber. The internal pressure of the pressurizing chamber is increased to contract the battery cell.

Description

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

[0001] The present invention relates to a battery cell quality inspection device capable of determining whether micro-cracks occur 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 from Republic of Korea Patent Application No. 10-2024-0039851, filed March 22, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Secondary batteries that can be recharged are attracting attention as power sources for devices that require high output and large capacity, including electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles, which are being proposed as a solution to air pollution caused by existing gasoline and diesel vehicles that use fossil fuels.

[0005] In terms of battery shape, there is a high demand for square secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones due to their thin thickness. In terms of materials, there is a high demand for lithium-ion batteries, such as lithium-ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.

[0006] These secondary batteries are also classified according to the structure of the electrode assembly of the positive electrode / separator / cathode structure. Representative examples include a jelly-roll electrode assembly having a structure in which long sheet-shaped positive and negative electrodes are rolled up with a separator interposed between them, a stacked electrode assembly having a plurality of positive and negative electrodes cut into units of a predetermined size and sequentially stacked with a separator interposed between them, and a stacked / folded electrode assembly having a structure in which bi-cells or full cells in which positive and negative electrodes of predetermined units are rolled up with a separator interposed between them.

[0007] Secondary batteries are structured to house an electrode assembly consisting of a positive electrode, a negative electrode, and a separator between them, along with an electrolyte, all housed in a battery case. As a device based on electrochemical reactions, they are inevitably sensitive to environmental factors. Furthermore, since they are manufactured through a series of processes in which small components are precisely mounted and connected in a confined space, errors in some devices or the inexperience of some workers can deteriorate product quality. Furthermore, in the mass production process of secondary batteries, even small flaws in the process can lead to serious defects.

[0008] Accordingly, secondary batteries must be meticulously inspected at every manufacturing stage and / or after the finished product is manufactured. This inspection is one of the most crucial aspects of secondary battery production, as it provides quality control to ensure that the batteries deliver the desired performance and stability. Quality control involves carefully assessing whether the secondary batteries have proper charge / discharge performance, producing good products while screening out defective ones. Proper quality control ensures the production of high-quality secondary batteries.

[0009] Microcracks within the battery case are one of the many causes of secondary battery failure. These microcracks can allow electrolyte to penetrate, potentially damaging the battery case's insulation and potentially leading to current leakage.

[0010] Conventionally, to detect microcracks like the ones described above, measuring instruments were connected to the battery case and electrode leads to measure leakage current. However, this method not only increases inspection time, but also presents the problem of electrolyte not adequately penetrating the microcracks, making it difficult to observe leakage current despite the presence of microcracks.

[0011] To address the above issues, a method has been introduced that involves physically pressurizing finished secondary batteries to artificially infiltrate electrolyte into microcracks and measure leakage current. However, this type of physical pressure can cause additional damage to the secondary battery case or internal electrode assembly, and therefore, existing inspection methods utilizing physical pressure are currently being avoided.

[0012]

[0013] (Prior art document) Korean Patent Publication No. 10-2023-0173521

[0014]

[0015] Accordingly, the present invention was created to solve the above problems, and its purpose is to provide an inspection device and an inspection method that can check whether an internal crack occurs without damaging a battery cell.

[0016] Other objects and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0017] According to the present invention, a battery cell quality inspection device is provided for measuring whether cracks occur inside a battery cell.

[0018] The battery cell quality inspection device comprises: a pressurized chamber that accommodates a battery cell therein; at least one pressurized unit coupled to the pressurized chamber to increase the pressure inside the pressurized chamber; and a measuring device that measures the insulation resistance of the battery cell accommodated inside the pressurized chamber; and is characterized in that the pressure inside the pressurized chamber is increased to shrink the battery cell.

[0019] The above pressurizing unit can increase pressure by injecting gas into the pressurizing chamber.

[0020] The above pressurized chamber may have a sealed structure to prevent gas from entering or exiting to the outside.

[0021] The pressurizing unit can pressurize the pressure inside the pressurizing chamber to a pressure of 3 bar to 30 bar.

[0022] The above pressurized chamber may have a strength that is not deformed by the pressure applied by the pressurized unit.

[0023] The above measuring instrument can be electrically connected to a battery cell housed inside the pressurized chamber to measure insulation resistance.

[0024] The above battery cell may include an electrode assembly in which electrodes and separators are alternately laminated, a pair of electrode leads electrically connected to the electrodes of the electrode assembly, a battery case that surrounds the electrode assembly so that the electrode leads are extended to the outside, and an electrolyte filled inside the battery case together with the electrode assembly.

[0025] The above measuring device is electrically connected to the battery case of the battery cell and one of the electrode leads to apply voltage and measure insulation resistance over time.

[0026] According to the present invention, a battery cell quality inspection method is provided for measuring whether cracks occur in a battery cell using the battery cell quality inspection device of the present invention.

[0027] The above battery cell quality inspection method comprises a first step of inserting a battery cell into a pressurized chamber equipped with a pressurized unit; a second step of connecting a measuring device to the battery cell; and a third step of increasing the pressure inside the pressurized chamber through the pressurized unit; characterized in that the insulation resistance of the battery cell is measured through the measuring device while increasing the pressure inside the pressurized chamber.

[0028] The pressurizing unit can pressurize the pressure inside the pressurizing chamber to a pressure of 3 bar to 30 bar.

[0029] The above insulation resistance can be obtained by the following equation 1.

[0030] [Formula 1]

[0031] Rx (insulation resistance) = Va / Ib

[0032] (Va is the voltage applied by the measuring instrument, and Ib is the leakage current.)

[0033] According to the present invention, it is possible to effectively check whether cracks occur inside a battery cell without damaging the battery cell being inspected.

[0034] Figure 1 is a schematic diagram simply showing the battery cell quality inspection device of the present invention.

[0035] Figure 2 is a plan view and a side view of a battery cell used for inspection.

[0036] Figure 3 is a cross-sectional view of a portion of the battery cell of Figure 2.

[0037] Figure 4 is a schematic diagram simply showing the measuring device of the present invention.

[0038] Figure 5 is a schematic diagram showing a modified example of the battery cell quality inspection device of the present invention.

[0039] Figure 6 schematically illustrates a process for a battery cell quality inspection method of the present invention.

[0040] Figure 7 is a cross-sectional view schematically showing deformation inside a battery cell due to pressure.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention, they should be construed as meanings and concepts consistent with the technical spirit of the present invention.

[0042] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0043] In addition, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description is omitted.

[0044] Since the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, the shapes and sizes of components in the drawings may be exaggerated, omitted, or schematically illustrated for clearer explanation. Accordingly, the sizes and proportions of each component do not fully reflect the actual sizes or proportions.

[0045]

[0046] The present invention relates to a battery cell quality inspection device capable of determining whether micro-cracks occur inside a battery cell, and a method for inspecting the quality of a battery cell using the same.

[0047] FIGS. 1 to 5 relate to a battery cell quality inspection device of the present invention, and FIGS. 6 to 7 relate to a battery cell quality inspection method of the present invention.

[0048] Hereinafter, specific embodiments of the battery cell quality inspection device and battery cell quality inspection method of the present invention will be described in detail with reference to the attached drawings. For reference, the directions of front / back, up / down / left / right, etc. used to designate relative positions in the following description are intended to aid understanding of the invention, and unless otherwise specified, the directions depicted in the drawings are taken as the reference.

[0049]

[0050] Battery cell quality inspection device (200)

[0051] The battery cell quality inspection device (200) of the present invention measures whether a crack (C) occurs inside a battery cell (100).

[0052] FIG. 1 is a schematic diagram simply showing a battery cell quality inspection device (200) of the present invention, FIG. 2 is a plan view and a side view of a battery cell (100) used for inspection, and FIG. 3 is a cross-sectional view of a part of the battery cell (100) of FIG. 2.

[0053]

[0054] The battery cell (100) that is the measurement target of the present invention has a pouch shape with the electrode lead (130) extending outward.

[0055] Specifically, the battery cell (100) is a pouch-type secondary battery including an electrode assembly (110) in which electrodes and a separator are alternately laminated, a pair of electrode leads (130) electrically connected to the electrodes of the electrode assembly (110), a battery case (120) that surrounds the electrode assembly (110) so that the electrode leads (130) are extended to the outside, and an electrolyte (140) filled inside the battery case (120) together with the electrode assembly (110).

[0056] The above electrode has an electrode tab (111) formed on one side and an active material coated on the surface.

[0057] Specifically, the electrode may be a positive electrode having a slurry of a positive electrode active material, a binder resin, a conductive agent, and other additives applied to at least one surface of a current collector, or a negative electrode having a slurry of a negative electrode active material, a binder resin, a conductive agent, and other additives applied to at least one surface of a current collector. Accordingly, the electrode assembly (110) is configured by alternately stacking a positive electrode, a separator, and a negative electrode.

[0058] The above electrode tab (111) is electrically connected by being joined in multiple layers to one electrode lead (130) as shown in FIG. 3.

[0059] One of the pair of electrode leads (130) included in the above battery cell (100) 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).

[0060] The above separator can be a conventional porous polymer film used in lithium secondary batteries.

[0061] The above battery case (120) 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.

[0062] The above pair of electrode leads (130) can be extended to one side of the battery case (120), and can be extended to both sides of the battery case (120) as shown in FIG. 2.

[0063] An insulating film (150) made of an insulating material is interposed between the contact point of the electrode lead (130) and the battery case (120), as shown in FIG. 3, and the battery case (120) can be insulated by the insulating film (150).

[0064] Although not shown in FIG. 3, the inside of the battery case (120) is filled with an electrolyte (140) together with an electrode assembly (110).

[0065] The above battery case (120) is maintained in a sealed state by welding or the like to prevent gas generated from the filled electrolyte (140) and the electrode assembly (110) from leaking to the outside.

[0066]

[0067] The above pressurized chamber (210) provides a space in which a battery cell (100) to be measured is installed.

[0068] It is preferable that the above pressurized chamber (210) has a strength that can withstand high pressure without being deformed by the increasing pressure when high pressure is applied to the battery cell (100) accommodated therein.

[0069] In addition, it is preferable that the pressurized chamber (210) has a sealed structure to prevent gas from entering or exiting to the outside.

[0070]

[0071] Figure 4 is a schematic diagram simply showing the measuring device (230) of the present invention.

[0072] The above measuring device (230) measures the insulation resistance of the battery cell (100) accommodated inside the pressurized chamber (210). More specifically, the measuring device (230) is electrically connected to the battery cell (100) accommodated inside the pressurized chamber (210) to measure the insulation resistance.

[0073] The battery cell quality inspection device (200) of the present invention can measure the insulation resistance of the battery cell (100) by inspecting the current of the battery cell (100) using the measuring device (230).

[0074] The above measuring instrument (230) includes a power unit (232), a leakage current, and a conductor (231) connecting the power unit (232) and the leakage current to the battery cell (100).

[0075] The measuring device (230) is electrically connected to the battery case (120) of the battery cell (100) and one of the electrode leads (130) using a conductor (231) as shown in FIGS. 1 and 4. The measuring device (230) is electrically connected to the battery case (120) and the electrode lead (130) as described above, thereby measuring the insulation resistance of the battery cell (100) over time.

[0076] The power unit (232) applies voltage to the battery cell (100), and the current measurement unit (233) measures leakage current.

[0077] The insulation resistance of the above battery cell (100) is obtained by the following equation 1.

[0078] [Formula 1]

[0079] Rx (insulation resistance) = Va / Ib

[0080] (Va is the voltage applied by the measuring instrument (230), and Ib is the leakage current.)

[0081]

[0082] The above pressurizing unit (220) is coupled to the pressurizing chamber (210) and serves to increase the pressure inside the pressurizing chamber (210).

[0083] That is, the battery cell quality inspection device (200) of the present invention 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 device (230) while the battery cell (100) is shrinking.

[0084] The pressurization unit (220) specifically increases the pressure by injecting gas into the pressurization chamber (210). Accordingly, the battery cell (100) accommodated inside the pressurization chamber (210) may be partially contracted due to the increasing pressure.

[0085] The pressurizing unit (220) preferably pressurizes the internal pressure of the pressurizing chamber (210) to 3 bar to 30 bar. At this time, 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).

[0086]

[0087] Figure 5 is a schematic diagram showing a modified example of the battery cell quality inspection device (200) of the present invention.

[0088] The battery cell quality inspection device (200) of the present invention may use at least one pressurizing unit (220). For example, two pressurizing units (220) may be used, as shown in FIG. 5.

[0089] When multiple pressurizing units (220) are provided in this way, the time required to reach the desired pressure can be effectively shortened.

[0090]

[0091] Battery cell (100) quality inspection method

[0092] Fig. 6 schematically illustrates a process for a method for inspecting the quality of a battery cell (100) of the present invention, and Fig. 7 is a cross-sectional view schematically illustrating deformation inside a battery cell (100) due to pressure.

[0093] Quality inspection of the battery cell (100) of the present invention is performed using the battery cell quality inspection device (200) of the present invention.

[0094] The quality inspection of the battery cell (100) of the present invention can be divided into several steps as shown in FIG. 6.

[0095]

[0096] Stage 1 (S1)

[0097] This is a step of inserting a battery cell (100) into a pressurizing chamber (210) equipped with a pressurizing unit (220).

[0098] The above battery cell (100) is placed inside a pressurized chamber (210) that can be sealed as shown in FIG. 6.

[0099]

[0100] Stage 2 (S2)

[0101] This is a step of connecting a measuring device (230) to the above battery cell (100).

[0102] In order to test the insulation resistance of the battery cell (100) placed inside the pressurized chamber (210), a measuring device (230) is electrically connected to the electrode lead (130) of the battery cell (100) and the battery case (120). For example, the measuring device (230) may be connected to the negative lead of the battery cell (100) and the battery case (120) via a conductor (231), respectively.

[0103] The above measuring instrument (230) applies voltage to the battery cell (100) and measures whether a leakage current occurs.

[0104] The applied voltage is 1 V to 2000 V.

[0105]

[0106] Stage 3 (S3)

[0107] This is a step of increasing the pressure inside the pressurizing chamber (210) through the pressurizing unit (220).

[0108] The method for inspecting the quality of a battery cell (100) of the present invention is characterized by increasing the pressure inside the pressurized chamber (210) and measuring the insulation resistance of the battery cell (100) through the measuring device (230).

[0109] Therefore, when the measuring instrument (230) is connected and ready to measure the insulation resistance of the battery cell (100), the pressurizing unit (220) is operated to increase the pressure inside the pressurizing chamber (210).

[0110] The pressure inside the pressurized chamber (210) is preferably 3 bar to 30 bar. At this time, if the pressure inside the pressurized chamber (210) is less than 3 bar, sufficient pressure cannot be transmitted to the battery cell (100), and if it exceeds 30 bar, there is a risk of damage to the battery cell (100).

[0111] The quality inspection of the battery cell (100) of the present invention controls the internal pressure of the pressurized chamber (210) within the above pressure range, observes whether a leakage current occurs in the battery cell (100), and obtains the insulation resistance of the battery cell (100) based on this.

[0112] The above insulation resistance is obtained by the following equation 1.

[0113] [Formula 1]

[0114] Rx (insulation resistance) = Va / Ib

[0115] (Va is the voltage applied by the measuring instrument (230), and Ib is the leakage current.)

[0116]

[0117] Voltage is applied to the battery cell (100) using the power unit (232) included in the measuring instrument (230), and leakage current is checked using the current measuring unit (233).

[0118] In the case of a normal battery cell (100), the battery case (120) will remain electrically insulated from the electrode assembly (110) or electrode lead (130), so there will be no leakage current observed through the measuring instrument (230).

[0119] Conversely, in the case of a battery cell (100) in which a micro-crack (C) has formed inside the battery case (120), the electrolyte (140) will penetrate into the micro-crack (C) due to external pressure, thereby breaking the insulation. Accordingly, leakage current is observed through the measuring device (230).

[0120] According to the above drawing 7, a part of the battery case (120) is pressed by pressure, and the 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) penetrates can be seen to have its internal insulation destroyed, and there is a possibility that a low voltage may occur or performance may deteriorate due to an internal short circuit.

[0121]

[0122] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0123]

[0124] (Explanation of symbols)

[0125] 100: Battery cell

[0126] 110: Electrode assembly

[0127] 111: Electrode tab

[0128] 120: Battery case

[0129] 130: Electrode lead

[0130] 140: Electrolyte

[0131] 150: Insulating film

[0132] 160: Case Film

[0133] 200: Battery cell quality inspection device

[0134] 210: Pressurized chamber

[0135] 220: Pressurized unit

[0136] 230: Measuring instrument

[0137] 231: Doseon

[0138] 232: Power unit

[0139] 233: Current measuring unit

[0140] C: Crack

[0141] S1: Stage 1

[0142] S2: Stage 2

[0143] S3: Stage 3

Claims

1. A battery cell quality inspection device that measures whether cracks occur inside a battery cell. A pressurized chamber containing battery cells inside; At least one pressurizing unit coupled to the pressurizing chamber to increase the pressure inside the pressurizing chamber; and A measuring instrument for measuring the insulation resistance of a battery cell accommodated inside the pressurized chamber; A battery cell quality inspection device characterized in that it increases the pressure inside the pressurized chamber to shrink the battery cell.

2. In paragraph 1, The above pressurization unit is a battery cell quality inspection device that increases pressure by injecting gas into the pressurization chamber.

3. In paragraph 1, The above pressurized chamber is a battery cell quality inspection device having a sealed structure to prevent gas from entering or exiting to the outside.

4. In paragraph 1, The above pressurizing unit is a battery cell quality inspection device that pressurizes the pressure inside the pressurizing chamber to 3 bar to 30 bar.

5. In paragraph 1, The above pressurized chamber is a battery cell quality inspection device having a strength that does not deform under the pressure applied by the pressurized unit.

6. In paragraph 1, The above measuring instrument is a battery cell quality inspection device that is electrically connected to a battery cell housed inside the pressurized chamber and measures insulation resistance.

7. In paragraph 1, A battery cell quality inspection device, wherein the battery cell is a pouch-type secondary battery, comprising an electrode assembly in which electrodes and separators are alternately laminated, a pair of electrode leads electrically connected to the electrodes of the electrode assembly, a battery case that surrounds the electrode assembly so that the electrode leads extend outward, and an electrolyte filled inside the battery case together with the electrode assembly.

8. In paragraph 8, The above measuring device is a battery cell quality inspection device that is electrically connected to the battery case of the battery cell and one of the electrode leads, applies voltage, and measures insulation resistance over time.

9. A battery cell quality inspection method for measuring whether cracks occur in a battery cell using the battery cell quality inspection device of paragraph 1, A first step of inserting a battery cell into a pressurized chamber equipped with a pressurized unit; A second step of connecting a measuring device to the above battery cell; and A third step of increasing the pressure inside the pressurizing chamber through the pressurizing unit; A battery cell quality inspection method characterized by increasing the pressure inside the pressurized chamber and measuring the insulation resistance of the battery cell through the measuring device.

10. In paragraph 9, A battery cell quality inspection method in which the pressurizing unit pressurizes the pressure inside the pressurizing chamber to a pressure of 3 bar to 30 bar.

11. In paragraph 9, The above insulation resistance is a battery cell quality inspection method obtained by the following equation 1. [Formula 1] Rx (insulation resistance) = Va / Ib (Va is the voltage applied by the measuring instrument, and Ib is the leakage current.)

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