Pouch battery cell sealing detection method

Abstract

The application provides a soft package battery cell sealing detection method, which comprises the following steps: vacuumizing the soft package battery cell after packaging; filling inert gas into the soft package battery cell; sealing the soft package battery cell and placing the soft package battery cell in a sealed cavity; vacuumizing the sealed cavity and standing for a preset time; detecting whether inert gas exists in the sealed cavity, if yes, the air tightness of the soft package battery cell is unqualified; if not, the air tightness of the soft package battery cell is qualified. The soft package battery cell sealing detection method effectively realizes comprehensive detection of the air tightness of the battery cell, can complete the air tightness detection of the soft package battery cell without damaging the soft package battery cell, is simple in overall operation, ensures the safety and performance stability of the soft package battery cell in the detection process and the later use process, and further solves the problems that the existing soft package battery cell air tightness detection method cannot be fully detected, influences the detection precision and is destructive to the battery cell itself.

Description

Technical Field

[0001] This application relates to the field of battery-related technology, and more specifically, to a method for testing the sealing performance of pouch cells. Background Technology

[0002] Pouch cells, as a thin, light, high-energy-density, and flexible lithium-ion battery packaging form, are widely used in consumer electronics, new energy vehicles, and energy storage systems. However, the gas-tightness of pouch cells is crucial to battery performance and safety. Even a tiny leak in the cell's packaging can lead to not only a decline in battery performance, such as capacity loss and increased internal resistance, but also safety hazards, such as thermal runaway.

[0003] The existing detection methods mainly include the following:

[0004] Thickness, sol-gel effect, and tensile strength testing of the aluminum-plastic film: This is the most basic testing method, which judges the airtightness by measuring the physical properties of the battery packaging material. However, this method can only indirectly reflect the packaging quality, is not effective in detecting minor airtightness defects, and cannot ensure the consistency of all cells.

[0005] Destructive testing: This involves placing the battery cell in simulated usage environments and conditions for testing. Although this testing method can assess the airtightness of the battery cell under extreme conditions, its destructive nature means that it can only be used for sampling inspection and cannot achieve full inspection.

[0006] Ultrasonic testing: This method utilizes the principles of ultrasonic transmission and reflection to inspect the integrity of the internal structure and packaging boundaries of battery cells. However, ultrasonic testing equipment is expensive, cannot achieve full inspection, and requires highly skilled operators, making it difficult to apply on a large scale in production lines.

[0007] Temperature cycling test: This method involves cycling the battery cell under high and low temperature conditions to observe the thermal expansion and contraction properties of the packaging material and evaluate its airtightness. However, this method is also destructive, has a long testing cycle, and cannot perform comprehensive testing, making it unsuitable for rapid testing on production lines.

[0008] In summary, the existing gas-tightness testing methods for pouch cells have the problems of not being able to perform full inspections, which affects the testing accuracy, and are also destructive to the cells themselves. Summary of the Invention

[0009] The main objective of this invention is to provide a method for testing the sealing performance of pouch cells, thereby solving the problems of existing pouch cell gas seal testing methods, which cannot perform full inspections, affecting testing accuracy, and are destructive to the cells themselves.

[0010] To achieve the above objectives, according to one aspect of the present invention, a method for testing the sealing performance of a pouch cell is provided, the method comprising the following steps:

[0011] Vacuuming is performed on the packaged soft-pack battery cells;

[0012] Fill the interior of the pouch cell with inert gas;

[0013] Seal the soft-pack battery cell and place the soft-pack battery cell inside the sealed cavity;

[0014] Evacuate the sealed cavity and let it stand for a preset time;

[0015] The presence of inert gas inside the sealed cavity is checked. If it is present, the airtightness of the pouch cell is unqualified; otherwise, the airtightness of the pouch cell is qualified.

[0016] Furthermore, the step of placing the pouch cell within the sealed cavity includes:

[0017] Several pouch cells are combined into a cell pack;

[0018] Several battery cell packs are placed inside a sealed cavity.

[0019] Furthermore, multiple pouch cells are stacked together to form a cell group; and / or multiple cell groups are spaced apart within a sealed cavity.

[0020] Furthermore, the step of placing the pouch cell inside the sealed cavity also includes: setting a pressure block of preset weight on the pouch cell, and the pressure block applying pressure to the sealed pouch cell.

[0021] Furthermore, the preset weight is 2kg.

[0022] Furthermore, the preset time is no less than 4 hours.

[0023] Furthermore, the pouch cell includes a cell body, a shell, and an air bag. The air bag and the cell body are located inside the shell. A vacuum is drawn by communicating with the air bag through a first vacuum generator. An inert gas at a preset pressure is filled into the vacuumed air bag by an inflation device, and the air bag is then sealed after being filled with inert gas.

[0024] Furthermore, the gas bag is sealed by heat sealing; and / or the interior of the gas bag is filled with 0.1 MPa of inert gas.

[0025] Furthermore, in the step of evacuating the sealed cavity, a second vacuum generator is connected to the sealed cavity to perform the evacuation.

[0026] Furthermore, in the step of detecting whether there is inert gas inside the sealed cavity, an inert gas detector connected to the sealed cavity is used to detect whether there is inert gas inside the sealed cavity.

[0027] By applying the technical solution of this invention, the airtightness testing method for pouch cells in this application adopts the steps of evacuating the pouch cell, filling it with inert gas, placing it in a sealed cavity, evacuating the sealed cavity, and testing the inert gas inside the sealed cavity. This effectively achieves a comprehensive test of the airtightness of the cell. Moreover, the above-mentioned testing method can complete the airtightness test of the pouch cell without damaging it. The overall operation is simple, ensuring the safety and performance stability of the pouch cell during the testing process and in subsequent use.

[0028] This application uses inert gas to fill the inside of the pouch cell as the detection medium, which can avoid contamination of the cell's interior. At the same time, by detecting inert gas in a sealed cavity under vacuum, minute gas leaks can be accurately detected, improving the accuracy and reliability of the detection. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 A flowchart of the method for testing the sealing performance of pouch cells according to the present invention is shown;

[0031] Figure 2 A schematic diagram of the detection structure of the pouch cell of the present invention is shown.

[0032] The above figures include the following reference numerals:

[0033] 10. Soft-pack battery cell; 20. Compression block; 30. Vacuum box; 310. Sealed cavity; 40. First vacuum generator; 50. Second vacuum generator; 60. Inert gas detector. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0036] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0037] To address the problems of existing pouch cell gas seal testing methods, which cannot perform full inspections affecting testing accuracy and are destructive to the cells themselves, this application provides a pouch cell sealing test method that achieves comprehensive testing of the pouch cell 10 without damaging its structure.

[0038] In this application, the airtightness of the packaged soft-pack battery cell 10 is tested, that is, the test object of this application is the packaged soft-pack battery cell 10.

[0039] In this embodiment, the sealing performance testing method for the pouch cell of this application mainly utilizes the internal air bag of the pouch cell 10, which is a component of the pouch cell 10. This application utilizes the structure of the pouch cell 10 itself to complete the entire sealing performance testing method, enabling the sealing performance testing of the pouch cell 10 without the need for tools such as cell puncture or cell damage, making the overall operation simple.

[0040] like Figure 1 As shown, the method for testing the sealing performance of pouch cells includes the following steps:

[0041] Vacuuming is performed on the packaged soft-pack battery cell 10;

[0042] Inert gas is filled into the interior of the pouch cell 10;

[0043] The soft-pack battery cell 10 is sealed and placed inside the sealed cavity 310;

[0044] Vacuum the sealed cavity 310 and let it stand for a preset time;

[0045] The presence of inert gas inside the sealed cavity 310 is checked. If it is, the airtightness of the soft-pack battery cell 10 is unqualified; if not, the airtightness of the soft-pack battery cell 10 is qualified.

[0046] By evacuating the pouch cell 10 to create a preset vacuum level inside the pouch cell 10, the air inside the cell can be effectively removed, providing a clean environment for subsequent inert gas injection, thereby improving the accuracy of the test.

[0047] In this embodiment, the preset vacuum level is -80 kPa. This vacuum level ensures that the gas inside the cell is fully expelled, creating conditions for the injection of inert gas. In the manufacturing of high-energy-density pouch cells 10, using this vacuum level can more effectively detect potential minute leaks, which is beneficial for improving detection accuracy and the effectiveness of comprehensive testing of the pouch cells 10.

[0048] Specifically, the airtightness testing method for the pouch cell of this application involves the following steps: evacuating the pouch cell 10, filling it with inert gas, placing it in the sealing cavity 310, evacuating the sealing cavity 310, and testing the inert gas inside the sealing cavity 310. This effectively achieves a comprehensive test of the airtightness of the cell. Moreover, the above testing method can complete the airtightness test of the pouch cell 10 without damaging it. The overall operation is simple, ensuring the safety and performance stability of the pouch cell 10 during the testing process and in subsequent use.

[0049] In this embodiment, the vacuum chamber 30 is used to provide a sealed cavity 310.

[0050] This application uses inert gas to fill the interior of the pouch cell 10 as the detection medium, which can avoid contamination of the cell interior. At the same time, by detecting inert gas in the sealed cavity 310 in a vacuum environment, minute gas leaks can be accurately detected, improving the comprehensiveness and accuracy of the detection.

[0051] Among them, the inert gas is helium or nitrogen, etc. It is understandable that helium and nitrogen are ideal choices for testing the airtightness of soft-pack battery cells because of their small molecular size, low reactivity with other substances and low cost.

[0052] In this embodiment, the inert gas is introduced at a pressure of 0.1 MPa. This pressure level ensures that the inert gas fully penetrates every corner of the cell, improving the comprehensiveness and accuracy of the test. The soft-pack cell 10 used in this application is filled with inert gas at a pressure of 0.1 MPa, which effectively avoids omissions due to insufficient pressure during testing. Simultaneously, the 0.1 MPa pressure ensures uniform distribution of the inert gas within the cell, which is beneficial for improving the efficiency of the airtightness test of the soft-pack cell 10.

[0053] In this embodiment, the pouch cell 10 includes a cell body, a shell, and an air bag. The air bag and the cell body are disposed inside the shell, wherein the shell is an aluminum-plastic film. The step of vacuuming the packaged pouch cell 10 in this application refers to vacuuming the inside of the air bag.

[0054] Specifically, the first vacuum generator 40 is connected to the air bag to perform vacuuming. Vacuuming the air bag with the first vacuum generator 40 helps to control the vacuum level inside the air bag, so as to adapt the vacuum level to different sizes and types of soft-pack battery cells 10.

[0055] The vacuum level used in this application is -80 kPa.

[0056] In this embodiment, the step of filling the interior of the pouch cell 10 with inert gas refers to filling the vacuum-sealed gas bag with inert gas at a preset pressure using an inflation device. The inflation device is used to provide the inert gas, and the preset pressure is 0.1 MPa.

[0057] In this embodiment, the step of sealing the soft-pack battery cell 10 refers to sealing the gas bag after it is filled with inert gas. Specifically, a heat sealing process is used to seal the gas bag in order to form a soft-pack battery cell 10 with inert gas at a preset pressure.

[0058] In this embodiment, the step of placing the pouch cell 10 inside the sealed cavity 310 includes:

[0059] Several pouch cells 10 are combined to form a cell group;

[0060] Several battery cell groups are placed inside the sealed cavity 310.

[0061] Among them, the air tightness test is carried out with the battery pack as the test unit. Each cell pack may include one pouch cell 10 or multiple pouch cells 10. When the cell pack includes multiple pouch cells 10, the multiple pouch cells 10 are stacked together. Each pouch cell 10 in the structure of the multiple pouch cells 10 is tested inside the accommodating cavity, which helps to improve the accuracy and efficiency of the air tightness test of the pouch cells 10.

[0062] Specifically, when multiple pouch cells 10 are set, if multiple pouch cells 10 have air leakage, more inert gas will leak into the sealed cavity 310, thereby improving the accuracy and efficiency of the detection.

[0063] In this embodiment, the number of pouch cells 10 can be 8, 10, 12, etc.

[0064] In this embodiment, one or more cell groups can be used. When multiple cell groups are used, they are arranged in a spaced-out manner inside the sealed cavity 310. This not only makes full use of space but also avoids mutual interference between cells, ensuring the accuracy of the test results. This method is suitable for testing pouch cells 10 of various sizes and shapes. By rationally arranging the cell groups, the space of the testing equipment can be maximized, while reducing electromagnetic interference and physical collisions between cells, ensuring that each cell can be tested independently and accurately. This layout is particularly suitable for mixed testing of multiple models and sizes of cells, providing battery manufacturers with a flexible and efficient testing solution.

[0065] In this embodiment, the step of placing the soft-pack battery cell 10 within the sealed cavity 310 further includes: placing a pressure block 20 of preset weight on the soft-pack battery cell 10, with the pressure block 20 applying pressure to the sealed soft-pack battery cell 10. By applying pressure, the stress conditions of the soft-pack battery cell 10 in actual use can be simulated, ensuring that the battery cell maintains good sealing performance under various conditions, making it suitable for battery cell testing that requires withstanding a certain amount of mechanical pressure. Furthermore, applying pressure to the soft-pack battery cell 10 to apply pressure to the air bag helps to improve the efficiency of airtightness testing.

[0066] The preset weight is 2kg. This weight selection simulates the pressure in actual use without causing excessive damage to the battery cells.

[0067] Among them, the pressure block 20 is made of metal, and the pressure block 20 can be a metal weight.

[0068] In this embodiment, the preset settling time is no less than 4 hours, specifically 4-8 hours. A long settling time allows for thorough testing of the cell's airtightness at different points in time, ensuring the cell's stability during long-term use, and is suitable for testing cells requiring long-term stable operation. A settling time of more than 4 hours allows for observation of changes in the cell's airtightness over different time periods, which is crucial for evaluating the cell's long-term safety and stability.

[0069] In this embodiment, as Figure 2 As shown, in the step of evacuating the sealed cavity 310, the second vacuum generator 50 is connected to the sealed cavity 310 to perform the evacuation.

[0070] Specifically, the second vacuum generator 50 can be used to fully evacuate sealed cavities 310 of different sizes. This independent vacuuming design avoids pressure interference between the pouch cell 10 and the sealed cavity 310, ensuring the accuracy of the test results and making it suitable for pouch cells 10 requiring high-precision testing. The second vacuum generator 50 evacuates the sealed cavity 310, eliminating the influence of internal pressure on the sealed cavity 310 and ensuring the independence and accuracy of the testing process.

[0071] In this embodiment, as Figure 2 As shown, in the step of detecting the presence of inert gas inside the sealed cavity 310, an inert gas detector 60 connected to the sealed cavity 310 detects the presence of inert gas inside the sealed cavity 310. This allows for real-time monitoring of gas changes within the sealed cavity 310, improving detection sensitivity and efficiency, and enabling rapid and accurate detection of minute gas leaks. The inert gas detector 60 can be a sensor, such as a nitrogen sensor or a helium sensor; alternatively, it can be a helium mass spectrometer. Helium mass spectrometers have extremely high sensitivity and accuracy, capable of detecting minute helium leaks, making them suitable for detecting soft-pack battery cells 10 with extremely high sealing requirements.

[0072] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0073] The airtightness testing method for the pouch cell of this application involves the following steps: evacuating the pouch cell 10, filling it with inert gas, placing it in a sealed cavity 310, evacuating the sealed cavity 310, and testing the inert gas inside the sealed cavity 310. This method effectively achieves a comprehensive test of the cell's airtightness. Furthermore, the above testing method can complete the airtightness test of the pouch cell 10 without damaging it. The overall operation is simple, ensuring the safety and performance stability of the pouch cell 10 during the testing process and in subsequent use.

[0074] This application uses inert gas to fill the interior of the pouch cell 10 as the detection medium, which can avoid contamination of the cell interior. At the same time, by detecting inert gas in the sealed cavity 310 in a vacuum environment, minute gas leaks can be accurately detected, improving the accuracy and reliability of the detection.

[0075] The sealing test method for pouch cells proposed in this application can be applied in the production process of pouch cells 10, which can significantly improve the production efficiency and yield of cells, reduce production costs, and provide strong technical support for the widespread application of pouch cells 10.

[0076] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0077] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0078] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for testing the sealing performance of a pouch cell, characterized in that, Includes the following steps: The packaged soft-pack battery cell (10) is evacuated; The interior of the pouch cell (10) is filled with inert gas; Seal the soft-pack battery cell (10) and place the soft-pack battery cell (10) inside the sealed cavity (310); The sealed cavity (310) is evacuated and left to stand for a preset time; The presence of the inert gas inside the sealed cavity (310) is detected. If it is, the airtightness of the soft-pack battery cell (10) is unqualified; if not, the airtightness of the soft-pack battery cell (10) is qualified. The step of placing the pouch cell (10) inside the sealed cavity (310) further includes: A pressure block (20) of preset weight is set on the soft-pack battery cell (10), and the pressure block (20) applies pressure to the sealed soft-pack battery cell (10); The soft-pack battery cell (10) includes a battery cell body, a shell, and an air bag, wherein the air bag and the battery cell body are disposed inside the shell; In the step of evacuating the packaged soft-pack battery cell (10), the vacuum is performed by connecting the first vacuum generator (40) to the air bag; In the step of filling the interior of the soft-pack battery cell (10) with inert gas, the inert gas at a preset pressure is filled into the vacuumed air bag by an inflation device. In the step of sealing the soft-pack battery cell (10) and placing the soft-pack battery cell (10) in the sealing cavity (310), the gas bag filled with the inert gas is sealed. The sealing test method for the soft-pack battery cell (10) can be used to test the sealing performance of the soft-pack battery cell (10) without the need for battery cell puncture or damage. The step of sealing the soft-pack battery cell (10) refers to sealing the gas bag after it is filled with inert gas, so as to form the soft-pack battery cell (10) with inert gas at a preset pressure.

2. The method for testing the sealing performance of pouch cells according to claim 1, characterized in that, The step of placing the pouch cell (10) within the sealed cavity (310) includes: A number of the aforementioned pouch cells (10) are formed into a cell group; Several of the battery cell groups are placed inside the sealed cavity (310).

3. The method for testing the sealing performance of pouch cells according to claim 2, characterized in that, Multiple pouch cells (10) are stacked together to form one cell group; and / or Multiple battery cell groups are spaced apart within the sealed cavity (310).

4. The method for testing the sealing performance of a pouch cell according to claim 1, characterized in that, The preset weight is 2kg.

5. The method for testing the sealing performance of a pouch cell according to claim 1, characterized in that, The preset time is no less than 4 hours.

6. The method for testing the sealing performance of a pouch cell according to any one of claims 1 to 5, characterized in that, The air bag is sealed by heat sealing; and / or The air bag is filled with 0.1 MPa of the inert gas.

7. The method for testing the sealing performance of a pouch cell according to any one of claims 1 to 5, characterized in that, In the step of evacuating the sealed cavity (310), the second vacuum generator (50) is connected to the sealed cavity (310) to perform the evacuation.

8. The method for testing the sealing performance of a pouch cell according to any one of claims 1 to 5, characterized in that, In the step of detecting whether the inert gas exists inside the sealed cavity (310), the presence of the inert gas inside the sealed cavity (310) is detected by an inert gas detector (60) connected to the sealed cavity (310).

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