Battery airtightness detection apparatus and method

Abstract

The present application is applicable in the technical field of power battery airtightness detection, and provides a battery airtightness detection apparatus and method. The battery airtightness detection apparatus comprises sealing chambers, a vacuumizing tube, and a gas injection tube. Multiple sealing chambers are provided. Each sealing chamber is used to contain at least one battery cell. A main body of the vacuumizing tube is located outside the sealing chamber, the vacuumizing tube is provided with a first gas port in communication with the sealing chamber, and the vacuumizing tube is used to place the sealing chamber in communication with an external vacuumizing system, and place the sealing chamber in communication with an external mass spectrometer. A main body of the gas injection tube is located outside the sealing chamber, the gas injection tube is provided with a second gas port located in the sealing chamber, the second gas port is used to be in communication with an inner cavity of the battery cell, and the gas injection tube is used to place the inner cavity of the battery cell in communication with an external tracer gas supply system. The battery airtightness detection apparatus and method provided by the present application can reduce vacuumizing duration, and decrease the difficulty of removing residual tracer gas.

Description

Battery airtightness detection device and method

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 24, 2023, with application number 202311580194.2 and invention name “Battery Airtightness Detection Device and Method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of power battery airtightness detection, and in particular relates to a battery airtightness detection device and method. Background Art

[0003] During the power battery manufacturing process, the weld sealing performance of battery cells is closely related to their safety throughout their lifecycle. Battery cells with poor airtightness pose a risk of leakage, which can easily lead to battery pack short circuits, fires, and failure. Therefore, efficient and accurate power battery airtightness testing is particularly important. Current battery airtightness testing devices and methods suffer from the problem of long vacuuming time.

[0004] Summary of the Invention

[0005] The purpose of the embodiments of the present application is to provide a battery airtightness detection device and method, aiming to improve the current battery airtightness detection device and method, which have the technical problem of long vacuuming time. Technical Solutions

[0006] The technical solution adopted in the embodiment of this application is:

[0007] In the first aspect, an embodiment of the present application provides a battery airtightness detection device, comprising: a plurality of sealed chambers; each of the sealed chambers is surrounded by at least two parts, and the sealed chamber is used to hold at least one battery cell; a vacuum pumping pipeline, the main body of the vacuum pumping pipeline is located outside the sealed chamber, the vacuum pumping pipeline has a first air port connected to the sealed chamber, the vacuum pumping pipeline is used to connect the sealed chamber with an external vacuum pumping system, and connect the sealed chamber with an external mass spectrometer; and a gas injection pipeline, the main body of the gas injection pipeline is located outside the sealed chamber, the gas injection pipeline has a second air port located in the sealed chamber, the second air port is used to connect with the inner cavity of the battery cell, and the gas injection pipeline is used to connect the sealed chamber with an external tracer gas supply system.

[0008] The battery airtightness testing device is provided with multiple sealed chambers for holding at least one battery cell, as well as vacuum pumping pipelines and gas injection pipelines connected to the sealed chambers. This makes it unnecessary to place all battery cells tested in the same batch in a large connected chamber for vacuum pumping and residual tracer gas removal when performing airtightness testing on battery cells using an external vacuum pumping system and an external tracer gas supply system. Only the sealed chambers holding some battery cells need to be vacuumed and residual tracer gas removed. This can reduce the time required for vacuum pumping to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers. The difficulty and time of removing residual tracer gas can be reduced to a certain extent, thereby improving the efficiency and accuracy of battery airtightness testing to a certain extent.

[0009] In some embodiments, the battery airtightness detection device further includes: a cavity having an opening and a plurality of sub-cavities therein; and a cover body, which is sealed on the opening of the cavity, wherein the side of the cover body facing the cavity and the inner walls of each sub-cavity form the sealed cavity; the vacuum pumping line is provided on the cover body or the cavity; and the gas injection line is provided on the cover body or the cavity. The sealed cavity is composed of the solution provided in this embodiment, which allows multiple sealed cavities to be assembled and transported as a whole. At the same time, the vacuum pumping line, gas injection line and sealed cavity can be combined into two parts, which facilitates the assembly and disassembly of the battery airtightness detection device and makes the structure of the entire battery airtightness detection device compact.

[0010] In some embodiments, the cavity includes: an outer shell having the opening; and a sub-shell, which is arranged in the outer shell, and the inner wall of the sub-shell forms the sub-cavity. By adopting the solution provided by this embodiment, the outer shell and the sub-shell can be prepared separately and then assembled together. In this way, sub-shells of the same specification or sub-shells of different specifications can be installed in the same outer shell according to the needs of use. This can expand the scope of application of the outer shell in the battery air tightness detection device to a certain extent and reduce the cost required for battery air tightness detection. And when the outer shell and the sub-shell are made of different materials, the production cost of the cavity can be reduced to a certain extent. In addition, if the outer shell adopts the cavity for holding multiple battery cells in the related art, the setting of the sub-shell can fill a part of the space of the cavity, so that after the battery cell is placed in the outer shell, the residual space between the inner wall of the outer shell is small, which can shorten the vacuuming time to a certain extent.

[0011] In some embodiments, the sub-shells are detachably mounted within the outer shell. This embodiment facilitates replacement of the sub-shells according to the size of the battery cells and facilitates replacement of damaged sub-shells. This improves the ease of use of the battery airtightness testing device, broadens the scope of application of the outer shell and sub-shells in the battery airtightness testing device, and reduces the cost of battery airtightness testing.

[0012] In some embodiments, a sealing layer is provided between two adjacent sub-shells, the sealing layer being in sealing contact with the cover. The provision of the sealing layer can ensure the seal between the sub-shells and the cover, as well as the separation between two adjacent sub-cavities, reduce crosstalk between gases within the sub-cavities, and improve the accuracy of airtightness testing.

[0013] In some embodiments, the sealing layer is disposed around the sub-shells, which can achieve a better sealing effect of the sealing layer.

[0014] In some embodiments, the sealing layer is an elastic layer; and / or the sealing layer is a rubber layer. Using an elastic layer for the sealing layer allows for better sealing contact with the cover, improving the sealing effect. Using a rubber layer for the sealing layer is inexpensive and provides a good sealing effect.

[0015] In some embodiments, a first plug-in portion is provided on the side of the split shell facing the cover; a second plug-in portion corresponding to the first plug-in portion is provided on the side of the cover facing the cavity, and the second plug-in portion is sealed and plugged into the first plug-in portion. The structure provided by this embodiment can increase the contact area between the split shell and the cover, achieving a better sealing effect. Furthermore, the connection between the first and second plug-in portions can also, to a certain extent, reduce the risk of swelling and indentation of the battery cells during tracer gas injection during airtightness testing of the battery cells.

[0016] In some embodiments, two first plug-in portions are provided and are disposed on two opposite side walls of the split shell, so that the forces on both sides of the split shell can be balanced.

[0017] In some embodiments, the first plug-in portion and the split shell are integrally formed, which can ensure a stable connection between the first plug-in portion and the split shell and facilitate production.

[0018] In some embodiments, the cover includes: a cover body that seals the opening of the cavity; and a cover body disposed on a side of the cover body facing the cavity. The cover body seals the opening of the sub-cavity and, together with the inner wall of the sub-cavity, forms a sealed chamber. The structure of the cover body provided in this embodiment allows the cover body and the cover body to be manufactured separately and then assembled together. This allows the same cover body to be equipped with cover bodies of the same or different specifications, depending on the application needs. This can broaden the applicability of the cover body in the battery airtightness testing device and reduce the cost of battery airtightness testing. Furthermore, when the cover body and the cover body are made of different materials, the manufacturing cost of the cavity can be reduced to a certain extent. Furthermore, if the cover body adopts the cover body used for cavities containing multiple battery cells in the related art, the provision of the cover body can fill a portion of the cavity space. This reduces the residual space between the battery cells placed in the housing and the inner wall of the space enclosed by the housing and the cover body, thereby shortening the vacuuming time.

[0019] In some embodiments, the cover body is detachably mounted on a side of the cover body facing the cavity. This embodiment facilitates replacement and maintenance of the cover body and the cover body, and can reduce the maintenance cost of the cover body to a certain extent.

[0020] In some embodiments, a mounting groove is provided on one side of the cover body facing the cavity, and at least a portion of the cover body is inserted into the mounting groove. The structure provided by this embodiment simplifies the structure of the cover body and the cover body, and facilitates assembly or separation of the cover body and the cover body.

[0021] In some embodiments, the dimension of the sealed chamber in at least one direction is 0.2 mm to 0.5 mm larger than the dimension of the battery cell. This ensures that after the battery cell is placed in the sealed chamber, the gap between the battery cell and the inner wall of the sealed chamber is sufficiently large, which can reduce the risk of the battery cell being crushed to a certain extent, thereby reducing the risk of damage to the battery cell during the airtightness test of the battery cell.

[0022] In a second aspect, a battery airtightness detection method is provided, which is based on the battery airtightness detection device provided by any of the above embodiments, including: evacuating a plurality of the sealed chambers until the vacuum degree in the sealed chamber is less than or equal to a first vacuum degree, each of the sealed chambers containing at least one battery cell; detecting the air pressure change in the battery cell to obtain an air pressure change value; judging whether the air pressure change value is less than a first threshold value; if the air pressure change value is less than the first threshold value, injecting a tracer gas into the battery cell through a tracer gas supply system; detecting the leakage rate of the battery cell; and judging whether the leakage rate is qualified.

[0023] The battery airtightness detection method provided in the embodiments of the present application utilizes the battery airtightness detection device provided in the aforementioned embodiments. This method can reduce the time required for vacuuming to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers. This can reduce the difficulty and time required to remove residual tracer gas to a certain extent, thereby improving the efficiency and accuracy of battery airtightness detection to a certain extent. Furthermore, by first performing a major leak test—that is, determining whether the air pressure change value is less than a first threshold value—and then performing a tracer gas leakage rate test, this can, to a certain extent, reduce the risk of severe contamination caused by large amounts of tracer gas entering sealed chambers, vacuum lines, etc.

[0024] In some embodiments, the first threshold is 1 kPa. The first threshold adopts the value provided in this embodiment, the detection requirements meet national standards, and the detection accuracy is high.

[0025] In some embodiments, the first vacuum degree is 40 Pa to 120 Pa. The first vacuum degree adopts the range of values ​​provided in this embodiment, which can meet the detection requirements and requires less energy consumption.

[0026] In some embodiments, the tracer gas includes helium or hydrogen. The tracer gas adopts the solution provided in this embodiment, which is easy to obtain and will not cause pollution or adverse effects on the battery cells.

[0027] In some embodiments, detecting the leakage rate of the battery cell includes: extracting tracer gas from the sealed chamber using a mass spectrometer to obtain tracer gas leak rate data over time; determining the battery leakage rate based on the leak rate data over time, wherein, when the slope is 0 ≤ k ≤ 5E-09 and the time is ≥ 2 seconds, the leak rate with the largest absolute value in the leak rate data over time is the battery leakage rate, wherein the slope k is calculated as follows: k = (y2 - y1) / (x2 - x1); where y1 is a first leak rate, y2 is a second leak rate adjacent to the first leak rate, x1 is the time corresponding to the first leak rate, and x2 is the time corresponding to the second leak rate. Using the solution provided in this embodiment, the operation time of step S5 can be shortened to a certain extent, thereby improving the efficiency of airtightness testing.

[0028] In some embodiments, if the air pressure change value is less than a first threshold, injecting a tracer gas into the battery cell via a tracer gas supply system includes: if the air pressure change value is less than the first threshold, evacuating the battery cell via a vacuum system until the vacuum level of the battery cell is less than or equal to a second vacuum level; and injecting a tracer gas into the battery cell via the tracer gas supply system. This can ensure accurate airtightness test results.

[0029] In some embodiments, the second vacuum degree is -95 kPa to -65 kPa. The second vacuum degree adopts the range of values ​​provided in this embodiment, which can meet the detection requirements and requires less energy consumption.

[0030] In some embodiments, after determining whether the leakage rate is qualified, the method further includes: evacuating the tracer gas in the battery cell, so as to prevent the tracer gas in the battery cell from continuously leaking into the sealed chamber to a certain extent.

[0031] In some embodiments, after determining whether the leakage rate is qualified, the method further includes: removing the tracer gas from the sealed chamber; opening the sealed chamber, and removing the battery cell. This allows the tracer gas to be removed within a smaller residual space, making it easier to remove the residual gas, maintaining a qualified background value in the testing environment, and reducing the impact of environmental noise.

[0032] In some embodiments, removing the tracer gas from the sealed chamber includes extracting residual gas from the sealed chamber until the vacuum level in the sealed chamber is less than or equal to a third vacuum level and the background value is less than or equal to a second threshold value. This can reduce environmental contamination by the tracer gas.

[0033] In some embodiments, the third vacuum level is -95 kPa, and the second threshold is 1E-07 Pa·m 3 The third vacuum degree and the second threshold value adopt the range values ​​provided in this embodiment, which can meet the detection requirements and require less energy consumption.

[0034] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] FIG1 is a schematic cross-sectional view of a battery airtightness detection device according to some embodiments of the present application;

[0037] FIG2 is a schematic cross-sectional view of a cavity and a cover in a battery airtightness detection device according to some embodiments of the present application;

[0038] FIG3 is a schematic diagram of the exploded structure of a battery airtightness detection device according to other embodiments of the present application;

[0039] FIG4 is a schematic cross-sectional view of a cavity and a cover in a battery airtightness detection device according to other embodiments of the present application;

[0040] FIG5 is a schematic diagram of an exploded structure of a separate shell and cover in a battery airtightness detection device according to some embodiments of the present application;

[0041] FIG6 is a schematic cross-sectional view of a battery airtightness detection device according to other embodiments of the present application;

[0042] FIG7 is a bottom view of the cover structure of the battery airtightness detection device in some embodiments of the present application;

[0043] FIG8 is a bottom view of the structure of a cover body in a battery airtightness detection device according to some embodiments of the present application;

[0044] FIG9 is a schematic flow chart of a battery airtightness detection method according to some embodiments of the present application;

[0045] FIG10 is a schematic flow chart of step S5 in the battery airtightness detection method according to some embodiments of the present application;

[0046] FIG11 is a flow chart of step S4 in the battery airtightness detection method according to some embodiments of the present application;

[0047] FIG12 is a flow chart of a battery airtightness detection method according to other embodiments of the present application;

[0048] FIG13 is a flow chart of a battery airtightness detection method according to other embodiments of the present application;

[0049] FIG14 is a schematic diagram of the structure of a battery cell;

[0050] FIG15 is a curve showing the change of leakage rate over time corresponding to samples 1 to 6.

[0051] The accompanying drawings in the specific implementation manner are as follows:

[0052] 10. Battery cell; 11. Large surface; 12. Side surface; 13. Top cover; 14. Explosion-proof disk; 15. Liquid injection hole; 16. Terminal;

[0053] 100, sealed chamber; 200, vacuum pumping line; 210, first gas port; 300, gas injection line; 310, second gas port; 400, cavity; 410, sub-cavity; 420, outer shell; 430, sub-shell; 440, first plug-in part; 450, sealing layer; 500, cover body; 510, second plug-in part; 520, cover body; 530, cover sub-body; 540, mounting groove. DETAILED DESCRIPTION

[0054] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0056] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0057] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0058] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, "and / or B" can represent three situations: the existence of "A" alone, the existence of "B" and "B" at the same time, and the existence of "B" alone. In addition, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0059] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0060] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0061] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0062] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0063] In the production and manufacturing process of power batteries, the welding sealing performance of battery cells is closely related to their safety issues throughout their life cycle. Battery cells with poor airtightness are at risk of leakage, which can easily lead to risks such as short circuit, fire, and failure of the battery pack. Therefore, efficient and accurate power battery airtightness testing is particularly important. The battery airtightness testing method usually adopts the vacuum cavity mass spectrometry detection method. The tracer gas can be helium or hydrogen, and the detection area is the top cover welding line and the sealing pin welding line. Due to production capacity requirements, airtightness testing equipment usually places several battery cells in the same cavity for testing. During the test, it is necessary to first evacuate the entire cavity for a large leak test, and then inject tracer gas into the battery cell. The leakage rate of the tracer gas is detected to determine whether the battery cell has a leak. When the leakage rate measured in any of the above two steps exceeds the preset range, the cavity is opened, and all the battery cells in the cavity are taken out for retesting to screen out defective products. Since a single battery cell is generally large in size, the volume of the cavity where several battery cells are placed is also large. This results in a long vacuum pumping time when performing airtightness testing of battery cells using the above method. At the same time, when a battery cell in the cavity leaks, the tracer gas injected into the battery cell will diffuse into the entire cavity, resulting in a high background value in the cavity and difficulty in removing the residual tracer gas.

[0064] To improve the above-mentioned problems, an embodiment of the present application provides a battery airtightness detection device and method. The battery airtightness detection device is provided with multiple sealed chambers for holding at least one battery cell, and a vacuum pumping pipeline and a gas injection pipeline connected to the sealed chamber. This makes it unnecessary to place all battery cells tested in the same batch in a large connected chamber for vacuum pumping and residual tracer gas removal when performing airtightness detection on battery cells through an external vacuum pumping system and an external tracer gas supply system. Only the sealed chambers holding some battery cells need to be vacuumed and residual tracer gas removed. This can reduce the time required for vacuum pumping to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers. The difficulty and time of removing residual tracer gas can be reduced to a certain extent, thereby improving the efficiency and accuracy of battery airtightness detection to a certain extent.

[0065] The battery airtightness detection device and method provided in the embodiments of the present application are suitable for battery airtightness detection, and are suitable for battery detection systems and battery production lines.

[0066] A battery production line typically includes a battery production system and a battery testing system. The battery testing system includes the aforementioned battery airtightness testing device. Furthermore, the battery testing system may also include dimensional testing equipment, depending on testing needs and is not intended to be a single limitation.

[0067] 1 , the battery airtightness detection device provided in an embodiment of the present application includes a sealed chamber 100 , a vacuum pumping line 200 , and a gas injection line 300 .

[0068] There are multiple sealed chambers 100 , each of which is used to contain at least one battery cell 10 .

[0069] The main body of the vacuum pumping line 200 is located outside the sealed chamber 100. The vacuum pumping line 200 has a first gas port 210 communicating with the sealed chamber 100. The vacuum pumping line 200 is used to connect the sealed chamber 100 with an external vacuum pumping system and to connect the sealed chamber 100 with an external mass spectrometer.

[0070] The main body of the gas injection pipeline 300 is located outside the sealed chamber 100. The gas injection pipeline 300 has a second gas port 310 located inside the sealed chamber 100. The second gas port 310 is used to communicate with the inner cavity of the battery cell 10. The gas injection pipeline 300 is used to connect the inner cavity of the battery cell 10 with the external tracer gas supply system.

[0071] It should be noted that the sealed chamber 100 in this embodiment is not an integrally formed structure, but is composed of multiple parts. It can be opened to place the battery cell 10 or take out the battery cell 10 located in the sealed chamber 100 according to the needs of use. The structures, materials, etc. of the various parts that enclose the sealed chamber 100 can be the same or different, which can be determined according to the needs of use. In some embodiments, a single sealed chamber 100 is used to place a single battery cell 10. In other embodiments, a single sealed chamber 100 is used to place two battery cells 10. In other embodiments, a single sealed chamber 100 is used to place other numbers of battery cells 10, but generally less than the number of battery cells 10, which can be determined according to the needs of use.

[0072] The vacuum line 200 has at least a first air port 210 and a communication port for communicating with an external vacuum system and an external mass spectrometer. It can be an integrally formed structure or can be composed of a plurality of tubes and / or connectors, and the specific structure can be determined according to the needs of use. It is understandable that the above-mentioned communication port can be one or two. When the communication port is one, a tee can be installed at the communication port to achieve simultaneous communication between the vacuum line 200 and the external vacuum system and the external mass spectrometer. In addition, the portion of the tee that is respectively connected to the external vacuum system and the external mass spectrometer can be installed with an on-off valve so that the vacuum line 200 can be connected to the external vacuum system and the external mass spectrometer according to the needs of use. That is, when the vacuum line 200 needs to be connected to the external vacuum system, the on-off valve between the vacuum line 200 and the external vacuum system is connected; when the vacuum line 200 needs to be connected to the external mass spectrometer, the on-off valve between the vacuum line 200 and the external mass spectrometer is connected.

[0073] The gas injection pipeline 300 comprises at least a second gas port 310 and a connection port for communicating with an external tracer gas supply system. It can be a one-piece structure or comprised of multiple tubes and / or connectors, depending on the intended use. It should be noted that an on-off valve is typically provided at the second gas port 310 or at the branch connecting the main line of the gas injection pipeline 300 to the second gas port 310. This allows the multiple second gas ports 310 to be connected or disconnected to the main line of the gas injection pipeline 300 by opening or closing the on-off valve.

[0074] The number of the first gas ports 210 and the second gas ports 310 is generally the same as the number of the sealed chambers 100 .

[0075] The principle of using the battery airtightness detection device provided in this embodiment to perform battery airtightness detection is as follows:

[0076] Before testing, multiple battery cells 10 to be tested in the same batch are placed in separate sealed chambers 100. The vacuum lines 200 are connected to an external vacuum system, and the gas injection lines 300 are connected to an external tracer gas supply system. A detection element is installed within each battery cell 10 to monitor its internal pressure. This detection element transmits detection signals to a control device located outside the sealed chamber 100 via an electrical connector or wireless transmission module.

[0077] After that, a major leak test is performed. During a major leak test, the vacuum system is first activated, and the sealed chamber 100 is evacuated via the vacuum system and vacuum pipeline 200. The control device receives data transmitted by the detection element in the battery cell 10 and determines whether the pressure change in the battery cell 10 meets the test requirements within a preset time period. If not, the airtightness of the corresponding battery cell 10 is determined to be unsatisfactory, and the test is terminated.

[0078] If it meets the requirements, the external tracer gas supply system is started, and the vacuum pipeline 200 is connected to the external mass spectrometer, and the tracer gas is injected into the corresponding battery cell 10 through the gas injection pipeline 300. Then, the tracer gas in the sealed chamber 100 is extracted through the external mass spectrometer and the vacuum pipeline 200 to determine whether the amount of tracer gas leaked into the sealed chamber 100 through the battery cell 10 within the preset time period is less than the preset threshold. If it is less than the preset threshold, it is determined that the airtightness test of the battery cell 10 in the corresponding sealed chamber 100 is qualified. If it is greater than or equal to the preset threshold, it is determined that the airtightness test of the battery cell 10 in the corresponding sealed chamber 100 is unqualified, and the battery cell 10 is a defective product.

[0079] Then, the tracer gas in the corresponding sealed chamber 100 is extracted through the external tracer gas supply system and the gas injection pipeline 300 until the residual tracer gas in the sealed chamber 100 meets the preset requirements. Then, the sealed chamber 100 is opened and the battery cell 10 therein is taken out.

[0080] The battery airtightness testing device provided in the embodiment of the present application is provided with multiple sealed chambers 100 for holding at least one battery cell 10, as well as a vacuum pumping line 200 and a gas injection line 300 connected to the sealed chamber 100. This makes it possible to perform airtightness testing on the battery cells 10 using an external vacuum pumping system and an external tracer gas supply system without placing all battery cells tested in the same batch in a large connected chamber for vacuum pumping and residual tracer gas removal. Instead, it is only necessary to perform vacuum pumping and residual tracer gas removal on the sealed chambers 100 containing some battery cells 10. In this way, the residual space between the battery cells 10 and the sealed chambers 100 after they are placed is small, which can reduce the time required for vacuum pumping to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers 100, which can reduce the difficulty and time of removing the residual tracer gas to a certain extent, thereby improving the efficiency and accuracy of battery airtightness testing to a certain extent.

[0081] As shown in Figures 1 and 2, in some embodiments, the battery airtightness detection device further includes a cavity 400 and a cover 500. The cavity 400 has an opening and is provided with a plurality of sub-cavities 410. The cover 500 seals the opening of the cavity 400. The surface of the cover 500 facing the cavity 400 and the inner walls of each sub-cavity 410 form a sealed chamber 100. The vacuum pumping line 200 is provided on the cover 500 or the cavity 400. The gas injection line 300 is provided on the cover 500 or the cavity 400.

[0082] The cavity 400 in this embodiment may be an integrally formed structure, or may be a split structure in which a large cavity 400 is provided with multiple sub-cavities for accommodating at least one battery cell, and the specific structure may be determined according to usage requirements.

[0083] The sub-cavity 410 refers to a chamber in the cavity 400 that is used to hold at least one battery cell 10 and has an opening.

[0084] The cover 500 may be an integrally formed structure or a split structure composed of multiple components, depending on the specific requirements.

[0085] By adopting the solution provided in this embodiment, multiple sealed chambers 100 can be assembled and transported as a whole. At the same time, the vacuum pumping line 200, the gas injection line 300 and the sealed chamber 100 can be combined into two parts, which facilitates the assembly and disassembly of the battery airtightness detection device and makes the structure of the entire battery airtightness detection device compact.

[0086] In some embodiments, as shown in FIG2 and FIG3 , the cavity 400 includes an outer shell 420 and a sub-shell 430 . The outer shell 420 has an opening. The sub-shell 430 is disposed within the outer shell 420 , and the inner wall of the sub-shell 430 encloses the sub-cavity 410 .

[0087] The housing 420 is generally formed in one piece and has a large inner cavity capable of accommodating multiple sub-housings 430. The housing 420 in this embodiment can adopt the cavity 400 used for accommodating multiple battery cells 10 in the aforementioned related art.

[0088] The sub-shell 430 also has an opening, and the opening direction is consistent with the opening direction of the outer shell 420. The inner cavity size of the sub-shell 430 is equivalent to the size of a single battery cell 10, or slightly larger than the size of a single battery cell 10, which can be determined according to usage requirements.

[0089] The materials of the sub-shell 430 and the outer shell 420 may be the same or different, depending on the specific requirements.

[0090] By adopting the solution provided in this embodiment, the outer shell 420 and the sub-shell 430 can be prepared separately and then assembled together. In this way, sub-shells 430 of the same specifications or sub-shells 430 of different specifications can be installed in the same outer shell 420 according to the needs of use. This can, to a certain extent, expand the scope of application of the outer shell 420 in the battery airtightness detection device and reduce the cost required for battery airtightness detection. Moreover, when the outer shell 420 and the sub-shell 430 are made of different materials, the production cost of the cavity 400 can be reduced to a certain extent. In addition, if the outer shell 420 adopts the cavity 400 used in the related art for holding multiple battery cells 10, the provision of the sub-shell 430 can fill a portion of the space in the cavity 400, so that after the battery cell 10 is placed in the outer shell 420, the residual space between the inner wall of the outer shell 420 is small, which can shorten the vacuuming time to a certain extent.

[0091] In some embodiments, the sub-shell 430 can be detachably disposed in the outer shell 420 .

[0092] Separably provided in the housing 420 means that the sub-housing 430 can be removed from the housing 420 as needed after being installed in the housing 420. For example, the sub-housing 430 can be detachably provided in the housing 420 by plugging, snapping, or directly placing.

[0093] The solution provided in this embodiment makes it easy for operators to replace the corresponding sub-shells 430 according to the size of the battery cell 10, and also facilitates the replacement of the sub-shells 430 after they are damaged. This can improve the convenience of using the battery airtightness detection device to a certain extent, expand the scope of application of the outer shell 420 and the sub-shells 430 in the battery airtightness detection device, and reduce the cost required for battery airtightness detection.

[0094] In some embodiments, as shown in FIG. 4 , a sealing layer 450 is disposed between two adjacent sub-shells 430 , and the sealing layer 450 is in sealing contact with the cover 500 .

[0095] The sealing layer 450 is a layer structure capable of performing a sealing effect.

[0096] The provision of the sealing layer 450 can ensure the seal between the sub-shell 430 and the cover 500 and the separation between two adjacent sub-cavities 410, reduce the mutual crosstalk of the gases in the sub-cavities 410, and improve the accuracy of the airtightness detection.

[0097] In some embodiments, the sealing layer 450 is disposed around the sub-shell 430. This can improve the sealing effect of the sealing layer 450.

[0098] In some embodiments, the sealing layer 450 is an elastic layer. An elastic layer means that the sealing layer 450 can deform when subjected to an external force and return to its original shape when the external force is removed. The use of an elastic layer for the sealing layer 450 allows for better sealing contact with the cover 500, improving the sealing effect.

[0099] In some embodiments, the sealing layer 450 is a rubber layer. The rubber layer is elastic and easy to obtain. The sealing layer 450 is made of a rubber layer, which is inexpensive and has a good sealing effect.

[0100] 5 , the split shell 430 has a first plug portion 440 on one side facing the cover 500 . The cover 500 has a second plug portion 510 on one side facing the cavity 400 , corresponding to the first plug portion 440 . The second plug portion 510 is sealed and plugged with the first plug portion 440 .

[0101] The first plug-in portion 440 can be integrally formed on the split shell 430, that is, the first plug-in portion 440 is a part of the split shell 430, or it can be an independent component prepared separately from the split shell 430 and fixed to the split shell 430 by welding, bonding, detachable connection, etc. There can be one or more first plug-in portions 440, which can be raised portions such as protrusions, bumps, etc., or recessed portions such as grooves, blind holes, etc.

[0102] The second plug-in portion 510 can be integrally formed on the cover 500, that is, the second plug-in portion 510 is a part of the cover 500, or it can be an independent component prepared separately from the cover 500 and fixed to the cover 500 by welding, bonding, detachable connection, etc. The number of the second plug-in portions 510 is the same as the number of the first plug-in portions 440. The shape and position of the second plug-in portion 510 can be determined based on the shape and position of the first plug-in portion 440. For example, if the first plug-in portion 440 is a raised portion, the second plug-in portion 510 is a recessed portion. If the first plug-in portion 440 is a recessed portion, the second plug-in portion 510 is a raised portion.

[0103] The structure provided in this embodiment can increase the contact area between the split shell 430 and the cover 500, improving the sealing effect. Furthermore, the first plug-in portion 440 and the second plug-in portion 510 can also reduce the risk of swelling and indentation of the battery cell 10 during the injection of tracer gas during the airtightness test of the battery cell 10.

[0104] In some embodiments, two first plug-in portions 440 are provided and are disposed on two opposite side walls of the split shell 430. This allows for balanced forces on both sides of the split shell 430.

[0105] In some embodiments, the first plug-in portion 440 is a protruding portion, and the second plug-in portion 510 is a recessed portion.

[0106] In this way, the volume and weight of the cover 500 can be reduced, making it easier to separate the cover 500 from the cavity 400 and to seal the cover 500 on the cavity 400 .

[0107] In some embodiments, the first plug-in portion 440 is integrally formed with the split shell 430. This can ensure a stable connection between the first plug-in portion 440 and the split shell 430 and facilitate manufacturing.

[0108] In some embodiments, the sub-shell 430 is made of stainless steel or Teflon.

[0109] The split shell 430 is made of stainless steel, which has good corrosion resistance, high hardness, good structural stability and long service life.

[0110] The split shell 430 is made of Teflon, which has the advantages of high temperature resistance, low temperature resistance, corrosion resistance, aging resistance, acid and alkali resistance, oxidation resistance, and insulation. It has good structural stability and a long service life.

[0111] In some embodiments, as shown in FIG6 , the cover 500 includes a cover body 520 and a cover body 530 . The cover body 520 seals the opening of the cavity 400 . The cover body 530 is disposed on the side of the cover body 520 facing the cavity 400 . The cover body 530 seals the opening of the sub-cavity 410 and, together with the inner wall of the sub-cavity 410 , forms a sealed chamber 100 .

[0112] The cover body 520 can be an integrally formed structural member or a combination of multiple components. The cover body 520 in this embodiment can adopt the cover body 500 in the cavity 400 for placing multiple battery cells 10 in the aforementioned related art.

[0113] The number of the cover parts 530 is generally the same as the number of the sub-cavities 410 . The material of the cover parts 530 can be the same as or different from the material of the cover body 520 , depending on the specific usage requirements.

[0114] The cover body 500 employs the structure provided in this embodiment, allowing the cover body 520 and the cover body 530 to be manufactured separately and then assembled together. This allows the same cover body 520 to be equipped with cover bodies 530 of the same or different specifications, depending on the intended use. This broadens the scope of application of the cover body 520 in battery airtightness testing devices and reduces the cost of battery airtightness testing. Furthermore, when the cover body 520 and the cover body 530 are made of different materials, the manufacturing cost of the cavity 400 can be reduced to a certain extent. Furthermore, if the cover body 520 employs the same cavity 400 as used in the related art for accommodating multiple battery cells 10, the provision of the cover body 530 can fill a portion of the cavity 400. This reduces the residual space between the battery cell 10 and the inner wall of the space enclosed by the outer shell 420 and the cover body 500 after placement within the outer shell 420, thereby shortening the vacuuming time to a certain extent.

[0115] In some embodiments, as shown in FIG. 7 and FIG. 8 , the cover body 530 is detachably mounted on a surface of the cover body 520 facing the cavity 400 .

[0116] Removable installation means that the cover body 530 can be installed on the side of the cover body 520 facing the cavity 400 by a detachable connection method such as plugging, snapping, etc., and the structure of the cover body 520 and the cover body 530 will not be damaged during disassembly.

[0117] The solution provided in this embodiment facilitates the replacement and maintenance of the cover body 520 and the cover split body 530 , and can reduce the maintenance cost of the cover body 500 to a certain extent.

[0118] In some embodiments, as shown in FIG. 7 and FIG. 8 , a mounting groove 540 is defined on a surface of the cover body 520 facing the cavity 400 , and at least a portion of the cover body 530 is inserted into the mounting groove 540 .

[0119] The structure provided in this embodiment makes the structures of the cover body 520 and the cover split body 530 simple, and facilitates the assembly or separation operation of the cover split body 530 and the cover body 520.

[0120] In some embodiments, the cover body 530 is made of stainless steel or Teflon.

[0121] The cover body 530 is made of stainless steel, which has good corrosion resistance, high hardness, good structural stability and long service life.

[0122] The cover body 530 is made of Teflon, which has the advantages of high temperature resistance, low temperature resistance, corrosion resistance, aging resistance, acid and alkali resistance, oxidation resistance, insulation, etc. It has good structural stability and a long service life.

[0123] In some embodiments, a dimension of at least one direction of the sealed chamber 100 is larger than a dimension of the battery cell 10 .

[0124] In this way, after the battery cell 10 is placed in the sealed chamber 100, there is a gap between it and the inner wall of the sealed chamber 100, which can reduce the risk of the battery cell 10 being crushed to a certain extent, thereby reducing the risk of damage to the battery cell 10 during the airtightness test of the battery cell 10.

[0125] In some embodiments, a dimension of at least one direction of the sealed chamber 100 is 0.2 mm to 0.5 mm larger than a dimension of the battery cell 10 .

[0126] As shown in Figure 1 , in the X direction, the dimension of the battery cell 10 is a1, and the dimension of the sealed chamber 100 is a2, where a2-a1 is 0.2mm-0.5mm. In Figure 1 , the X direction represents the thickness of the battery cell. In other embodiments, the dimensions of the sealed chamber 100 in other directions may be larger than those of the battery cell 10, depending on the intended use.

[0127] In this way, after the battery cell 10 is placed in the sealed chamber 100, the gap between it and the inner wall of the sealed chamber 100 is large enough, which can reduce the risk of the battery cell 10 being crushed to a certain extent, thereby reducing the risk of damage to the battery cell 10 during the airtightness test of the battery cell 10.

[0128] According to some embodiments of the present application, the present application further provides a battery detection system, including the battery airtightness detection device provided by any of the above embodiments.

[0129] The battery testing system provided in the embodiments of the present application adopts the battery airtightness testing device provided in the above-mentioned embodiments, which can reduce the time required for vacuuming to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers. It can reduce the difficulty and time of removing residual tracer gas to a certain extent, thereby improving the efficiency and accuracy of battery airtightness testing to a certain extent.

[0130] According to some embodiments of the present application, the present application also provides a battery production line, including the battery airtightness detection device provided by any of the above embodiments.

[0131] The battery production line provided in the embodiments of the present application adopts the battery airtightness detection devices provided in the above embodiments, which can reduce the time required for vacuuming to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers, which can reduce the difficulty and time of removing residual tracer gas to a certain extent, thereby improving the efficiency and accuracy of battery airtightness detection to a certain extent.

[0132] According to some embodiments of the present application, as shown in FIG9 , the present application further provides a battery airtightness detection method, including but not limited to the following steps:

[0133] S1. Evacuate multiple sealed chambers until the vacuum level in the sealed chamber is less than or equal to a first vacuum level, and each sealed chamber contains at least one battery cell.

[0134] The vacuum operation can be achieved through a vacuum system.

[0135] S2. Detect the air pressure change in the battery cell and obtain the air pressure change value.

[0136] The air pressure change value in this step can be calculated using data obtained by an air pressure sensor provided in the battery cell.

[0137] S3. Determine whether the air pressure change value is less than a first threshold.

[0138] The first threshold can be derived based on testing experience. This first threshold is used to determine whether a battery cell has a leak. If the pressure change is greater than or equal to the first threshold, the battery cell can be directly determined to have a leak and is defective. If the pressure change is less than the first threshold, further testing is required to determine whether the battery cell is acceptable.

[0139] S4. If the pressure change value is less than the first threshold, inject tracer gas into the battery cell through the tracer gas supply system.

[0140] The injection of tracer gas can be achieved through a tracer gas supply system and a gas injection pipeline.

[0141] S5. Detect the leakage rate of the battery cells.

[0142] The leakage rate can be obtained by extracting the gas in the sealed chamber through a mass spectrometer and a vacuum pipeline, and detecting the change of the tracer gas amount in the gas over time.

[0143] S6. Determine whether the leakage rate is qualified.

[0144] If the leakage rate is less than the preset range, it is considered qualified and the corresponding battery cell is judged to meet the airtightness requirements and is a qualified product. If the leakage rate is greater than or equal to the preset range, it is considered unqualified and the corresponding battery cell is judged to have a leak point and is a defective product.

[0145] The battery airtightness detection method provided in the embodiments of the present application utilizes the battery airtightness detection device provided in the aforementioned embodiments. This method can reduce the time required for vacuuming to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers. This can reduce the difficulty and time required to remove residual tracer gas to a certain extent, thereby improving the efficiency and accuracy of battery airtightness detection to a certain extent. Furthermore, by first performing a major leak test—that is, determining whether the air pressure change value is less than a first threshold value—and then performing a tracer gas leakage rate test, this can, to a certain extent, reduce the risk of severe contamination caused by large amounts of tracer gas entering sealed chambers, vacuum lines, etc.

[0146] In some embodiments, the first threshold is 1 kPa.

[0147] The first threshold value adopts the value provided in this embodiment, the detection requirement complies with the national standard, and the detection accuracy is high.

[0148] In some embodiments, the first vacuum degree is an absolute vacuum degree, which is 40 Pa to 120 Pa. The first vacuum degree adopts the range of values ​​provided in this embodiment, which can meet the detection requirements and requires less energy consumption.

[0149] In some embodiments, the tracer gas includes helium or hydrogen. When the tracer gas includes helium, the purity of the helium is 99.999%. When the tracer gas includes hydrogen, the tracer gas generally comprises 3% to 5.5% hydrogen and 94.5% to 97% nitrogen, with the sum of the volume fractions of hydrogen and nitrogen being 100%. The tracer gas employed in this embodiment is easy to obtain and does not contaminate or adversely affect the battery cells.

[0150] In some embodiments, as shown in FIG10 , step S5 of detecting the leakage rate of the battery cell 10 includes but is not limited to the following steps:

[0151] S51 . Extracting tracer gas in the sealed chamber 100 through a mass spectrometer to obtain data on the variation of the tracer gas leakage rate over time.

[0152] The above-mentioned leak rate variation data can be generated directly by a mass spectrometer or calculated by observing the total amount of tracer gas extracted by the mass spectrometer at different times. This is not a single limitation. Leak rate variation data typically provides a one-to-one correspondence between detection time and leak rate.

[0153] The above-mentioned leakage rate variation data over time can be presented in the form of a data table, or in the form of a curve graph, a dot graph, etc., as shown in FIG15 , and the specific form can be determined according to the use requirements.

[0154] S52. Obtain the battery leakage rate from the leakage rate variation data over time. When the slope is 0≤k≤5E-09 and the time is ≥2s, the leakage rate with the largest absolute value in the leakage rate variation data over time is the battery leakage rate. The slope k is calculated as follows: k=(y2-y1) / (x2-x1);

[0155] Wherein, y1 is a first leak rate, y2 is a second leak rate adjacent to the first leak rate, x1 is the time corresponding to the first leak rate, and x2 is the time corresponding to the second leak rate.

[0156] The leak rate with the largest absolute value is the leak rate with the largest absolute value among all leak rates that satisfy the slope k≤5E-09 and the time≥2s.

[0157] By adopting the solution provided in this embodiment, the operation time of step S5 can be shortened to a certain extent, thereby improving the efficiency of airtightness detection.

[0158] In some embodiments, as shown in FIG11 , step S4 includes:

[0159] S41: If the pressure change value is less than the first threshold, vacuum the battery cell through the vacuum system until the vacuum degree of the battery cell is less than or equal to the second vacuum degree;

[0160] S42. Injecting tracer gas into the battery cell through the tracer gas supply system.

[0161] This can ensure accurate airtightness test results.

[0162] In some embodiments, the second vacuum degree is -95 kPa to -65 kPa. The second vacuum degree adopts the range of values ​​provided in this embodiment, which can meet the detection requirements and requires less energy consumption.

[0163] In some embodiments, as shown in FIG12 , after step S6 determines whether the leakage rate is qualified, the following steps are further performed:

[0164] S7. Evacuate the tracer gas in the battery cell.

[0165] This operation can be achieved through the gas injection pipeline and an external tracer gas supply system, or by connecting the gas injection pipeline to an external vacuum system, or by connecting the gas injection pipeline to other gas extraction systems, depending on the specific needs.

[0166] Evacuating the tracer gas from the battery cell can, to a certain extent, prevent the tracer gas from continuously leaking from the battery cell into the sealed chamber.

[0167] In some embodiments, as shown in FIG13 , after determining whether the leakage rate is qualified in step S6, the following steps are further included:

[0168] S8. Clear the tracer gas in the sealed chamber.

[0169] This operation can be achieved through a vacuum pumping line and an external vacuum pumping system, or through a vacuum pumping line and a mass spectrometer, or through a vacuum pumping line connected to other exhaust systems, depending on the specific needs.

[0170] S9. Open the sealed chamber and remove the battery cell. By removing the tracer gas from the sealed chamber, the tracer gas can be removed within a smaller residual space, making it easier to remove the residual gas, maintaining a qualified background value in the testing environment, and reducing the impact of environmental noise. This background value refers to the signal value of the detector (such as an external mass spectrometer) when no sample is injected. It depends on the detector type and is a value that cannot be removed in any way.

[0171] In some embodiments, step S8, clearing the tracer gas in the sealed chamber, includes but is not limited to the following steps:

[0172] Residual gas in the sealed chamber is extracted until the vacuum level in the sealed chamber is less than or equal to the third vacuum level and the background value is less than or equal to the second threshold value.

[0173] This can reduce the pollution of tracer gas to the environment.

[0174] In some embodiments, the third vacuum level is -95 kPa, and the second threshold is 1E-07 Pa·m 3 / s.

[0175] The third vacuum degree and the second threshold value adopt the range values ​​provided in this embodiment, which can meet the detection requirements and require less energy consumption.

[0176] According to some embodiments of the present application, as shown in Figures 1 to 8 , a battery airtightness detection device is provided, which includes a sealed chamber 100 , a vacuum pumping line 200 , and a gas injection line 300 .

[0177] There are a plurality of sealed chambers 100 . Each sealed chamber 100 is surrounded by at least two parts and is used to contain at least one battery cell 10 .

[0178] The main body of the vacuum pumping line 200 is located outside the sealed chamber 100. The vacuum pumping line 200 has a first gas port 210 communicating with the sealed chamber 100. The vacuum pumping line 200 is used to connect the sealed chamber 100 with an external vacuum pumping system and to connect the sealed chamber 100 with an external mass spectrometer.

[0179] The main body of the gas injection pipeline 300 is located outside the sealed chamber 100. The gas injection pipeline 300 has a second gas port 310 located inside the sealed chamber 100. The second gas port 310 is used to communicate with the inner cavity of the battery cell 10. The gas injection pipeline 300 is used to connect the inner cavity of the battery cell 10 with the external tracer gas supply system.

[0180] The battery airtightness detection device also includes a cavity 400 and a cover body 500. The cavity 400 includes an outer shell 420 and a sub-shell 430. The outer shell 420 has an opening. The sub-shell 430 is detachably arranged in the outer shell 420. The inner wall of the sub-shell 430 surrounds the sub-cavity 410. The cover body 500 includes a cover body 520 and a cover sub-body 530. The cover body 520 is sealed at the opening of the cavity 400. The cover body 520 is provided with an installation groove on the side facing the cavity 400, and at least part of the cover sub-body 530 is inserted into the installation groove. The cover sub-body 530 is correspondingly sealed at the opening of the sub-cavity 410, and forms a sealed chamber 100 with the inner wall of the sub-cavity 410. The cover sub-body 530 is a stainless steel part or a Teflon part.

[0181] A sealing layer 450 is provided between two adjacent sub-shells 430. The sealing layer 450 is in sealing contact with the cover 500. The sealing layer 450 surrounds the sub-shells 430. This allows for a better sealing effect of the sealing layer 450. The sealing layer 450 is a rubber layer.

[0182] The side of the sub-shell 430 facing the cover 500 is provided with a raised portion. The side of the cover 500 facing the cavity 400 is provided with a recessed portion corresponding to the first plug-in portion 440. The recessed portion and the raised portion are sealed and plugged into each other. The sub-shell 430 is made of stainless steel or Teflon.

[0183] The battery airtightness detection device provided in this embodiment adopts a sub-cavity 410 design for a large chamber originally used to place multiple battery cells 10. The sub-cavity 410 reduces the residual space between the battery cells 10 and the sealed chamber 100 by arranging filling blocks such as a sub-shell 430 and a sub-cover 530 in the above-mentioned large chamber.

[0184] When conducting an airtightness test on a battery cell 10, the battery cell 10 can first be clamped by a robot and placed in the cavity 400. At this time, the cavity 400 and the cover 500 are in a separated state as shown in FIG3 . The cavity 400 is then lifted upward to merge with the cover 500, and the cover 500 and the sealing layer 450 are compacted to form a sealed chamber 100. The sealed chamber is then evacuated by the pump, evacuation pipeline, and vacuum pipeline in the vacuum system to perform a major leak test. When performing a major leak test, the air pressure change value in the battery cell can be detected by the air pressure sensor in the battery cell. If the air pressure change value is greater than or equal to the first threshold value, the battery cell has a leak point and is a defective product, and the test is completed. If the air pressure change value is less than the first threshold value, the next test is performed.

[0185] Tracer gas is injected into battery cells 10 that have passed the above-mentioned major leak test (i.e., battery cells 10 with a pressure change value less than the first threshold), and the leakage rate of the battery cells 10 is detected using a mass spectrometer. If the leakage rate exceeds the specification, the battery cell has a leak point and is defective. The test is then completed. The tracer gas in the battery cell is then evacuated using a pump and gas injection pipeline. The residual tracer gas in the sealed chamber is removed using a pump and vacuum pipeline. The tracer gas volume in the sealed chamber is detected using a mass spectrometer. If it meets the requirements, the sealed chamber is opened and the battery cell is removed. If it does not meet the requirements, the residual tracer gas in the sealed chamber is further removed using the pump and vacuum pipeline, and the above steps are repeated. If the leakage rate test passes, the battery cell is considered to be qualified.

[0186] The battery airtightness detection device provided in the embodiment of the present application adopts a divided chamber and complementary filling design, with a small residual space in the chamber and a short vacuuming time. The divided chamber design prevents residual tracer gas from contaminating adjacent chambers, effectively avoiding severe contamination of the chamber during large leak detection, and the closed chamber method for removing residual tracer gas is fast and efficient.

[0187] The aforementioned sub-cavity design employs a corresponding sub-cavity 410 for each battery cell 10, with the sub-shell 430 and the cover 530 complementing each other. The limiting dimensions of the side surfaces 12, large surface 11, and top cover 13 of the battery cell 10 are 0.2mm to 0.5mm. This means that the side surfaces, large surface, and top cover dimensions of the sealed chamber 100 are 0.2mm to 0.5mm larger than the corresponding dimensions of the battery cell 10. Referring to Figures 1 and 14 , in some embodiments, the side surfaces of the sealed chamber 100 are 0.4mm larger than the side surfaces 12 of the battery cell 10, and the top surface is 0.2mm larger than the top cover 13 of the battery cell 10 to prevent damage to structures on the battery cell, such as the terminal 16.

[0188] The principle of the above-mentioned major leak detection is that the sealed chamber 100 is vacuumed first. If there is a large leak hole in the battery cell 10, the gas pressure inside the battery cell 10 will be significantly reduced. The sealed chamber 100 is vacuumed, and the absolute vacuum degree needs to be less than 40Pa~120Pa. If the change in the internal gas pressure value of the battery cell 10 is greater than or equal to 1kPa, it is considered that there is a large leak hole in the battery cell 10, that is, there is a major leak.

[0189] The tracer gas is one of helium or hydrogen, wherein the purity of the injected helium gas is 99.999%, and the composition of the injected hydrogen gas is a mixture of 3% to 5.5% hydrogen and 94.5% to 97% nitrogen, and the sum of the volume fractions of hydrogen and nitrogen is 100%.

[0190] In the above operation process, before injecting the tracer gas into the battery cell 10 , the gas inside the battery cell 10 needs to be evacuated first, and the evacuation pressure of the battery cell 10 is -95 kPa to -65 kPa.

[0191] When the cavity is closed and the tracer gas remaining in the cavity 400 is removed, the vacuum degree should be less than -95kPa, and the background value should be less than 1E-07Pa·m 3 / s.

[0192] Injecting the tracer gas into the battery cells 10 that have passed the major leak detection (i.e., the battery cells 10 whose gas pressure change value is less than the first threshold) is to inject the tracer gas into the battery cells 10 through the gas injection pipeline 300 and the liquid injection hole 15 on the battery cells 10 .

[0193] The specific operation of detecting the leakage rate of the battery cell 10 by the mass spectrometer is as follows:

[0194] During the tracer gas leakage detection process, the battery leakage rate is obtained by the leakage rate variation over time. When the slope is 0≤k≤5E-09 and the time is ≥2s, the corresponding leakage rate is the battery leakage rate. The slope k is calculated as: k=(y2-y1) / (x2-x1);

[0195] Wherein, y1 is a first leak rate, y2 is a second leak rate adjacent to the first leak rate, x1 is the time corresponding to the first leak rate, and x2 is the time corresponding to the second leak rate.

[0196] If the leakage rate is greater than or equal to 1E-06Pa·m 3 / s, it is considered that the leakage rate of the battery cell 10 exceeds the specification.

[0197] For ease of understanding, we used 6 samples for testing, as shown in Figure 15. By calculating the slope and the time ≥ 2s, it can be determined that when the time is 3.4s, the leakage rate response of the battery cell reaches a steady-state value, and the leakage rate at this time is the final leakage rate of the battery.

[0198] The comparison of the evacuation time and the time required to reach the background value standard in the embodiment of the present application and the conventional airtightness detection is shown in the following table:

[0199] After testing, the battery airtightness detection device and method provided in the embodiments of the present application saves more than 50% of the vacuuming time compared with conventional airtightness detection; the chamber design prevents residual gas from contaminating adjacent chambers, and large leak detection effectively avoids severe contamination of the chamber. The closed-chamber method for removing residual gas is fast and efficient, saving more than 90% of the time compared with conventional airtightness detection.

[0200] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery airtightness detection device, characterized in that: include: A plurality of sealed chambers are provided; the sealed chamber is used to contain at least one battery cell; A vacuum pumping pipeline, wherein the main body of the vacuum pumping pipeline is located outside the sealed chamber, the vacuum pumping pipeline has a first air port connected to the sealed chamber, and the vacuum pumping pipeline is used to connect the sealed chamber with an external vacuum pumping system and connect the sealed chamber with an external mass spectrometer; as well as The gas injection pipeline has a main body located outside the sealed chamber, and has a second gas port located in the sealed chamber, the second gas port is used to communicate with the inner cavity of the battery monomer, and the gas injection pipeline is used to connect the inner cavity of the battery monomer with an external tracer gas supply system.

2. The battery airtightness detection device according to claim 1, characterized in that: The battery airtightness detection device also includes: A cavity having an opening and a plurality of sub-cavities therein; and A cover body, covering the opening of the cavity, wherein a surface of the cover body facing the cavity and the inner walls of each of the sub-cavities form the sealed chamber; The vacuum extraction pipeline is arranged on the cover body or the cavity; the gas injection pipeline is arranged on the cover body or the cavity.

3. The battery airtightness detection device according to claim 2, characterized in that: The cavity comprises: a housing having the opening; and The sub-shell is arranged in the outer shell, and the inner wall of the sub-shell surrounds the sub-cavity.

4. The battery airtightness detection device according to claim 3, characterized in that: The sub-shell is detachably arranged in the outer shell.

5. The battery airtightness detection device according to claim 3 or 4, characterized in that: A sealing layer is provided between two adjacent sub-shells, and the sealing layer is in sealing contact with the cover body.

6. The battery airtightness detection device according to claim 5, characterized in that: The sealing layer is arranged around the sub-shell.

7. The battery airtightness detection device according to claim 5 or 6, characterized in that: The sealing layer is an elastic layer; And / or, the sealing layer is a rubber layer.

8. The battery airtightness detection device according to any one of claims 3 to 7, characterized in that: A first plug-in portion is provided on one side of the split shell facing the cover body; A second plug-in portion corresponding to the first plug-in portion is disposed on one side of the cover body facing the cavity, and the second plug-in portion is sealed and plugged with the first plug-in portion.

9. The battery airtightness detection device according to claim 8, characterized in that: The first plug-in parts are provided with two and are respectively arranged on two oppositely arranged side walls of the split shell.

10. The battery airtightness detection device according to claim 8 or 9, characterized in that: The first plug-in portion and the split shell are integrally formed.

11. The battery airtightness detection device according to any one of claims 2 to 10, characterized in that: The cover body comprises: a cover body, sealing the opening of the cavity; and The cover body is provided on the side of the cover body facing the cavity, and the cover body is corresponding to the opening of the sub-cavity. The opening is located at the bottom of the chamber and together with the inner wall of the sub-chamber, forms the sealed chamber.

12. The battery airtightness detection device according to claim 11, characterized in that: The cover body is detachably mounted on a side of the cover body facing the cavity.

13. The battery airtightness detection device according to claim 12, characterized in that: A mounting groove is provided on a side of the cover body facing the cavity, and at least a portion of the cover body is inserted into the mounting groove.

14. The battery airtightness detection device according to any one of claims 1 to 13, characterized in that: The dimension of the sealed chamber in at least one direction is 0.2 mm to 0.5 mm larger than the dimension of the battery cell.

15. A battery airtightness detection method, based on the battery airtightness detection device according to any one of claims 1 to 14, characterized in that: include: Evacuating the plurality of sealed chambers until the vacuum degree in the sealed chambers is less than or equal to the first vacuum degree, each of the sealed chambers containing at least one battery cell; Detecting the change of air pressure in the battery cell to obtain an air pressure change value; Determining whether the air pressure change value is less than a first threshold; If the pressure change value is less than a first threshold, injecting a tracer gas into the battery cell through a tracer gas supply system; detecting a leakage rate of the battery cell; Determine whether the leakage rate is qualified.

16. The battery airtightness detection method according to claim 15, characterized in that: The first threshold is 1 kPa.

17. The battery airtightness detection method according to claim 15 or 16, characterized in that: The first vacuum degree is 40Pa-120Pa.

18. The battery airtightness detection method according to any one of claims 15 to 17, characterized in that: The tracer gas includes helium or hydrogen.

19. The battery airtightness detection method according to claim 15, characterized in that: The detecting the leakage rate of the battery cell comprises: Extracting tracer gas in the sealed chamber by means of a mass spectrometer to obtain data on the variation of the tracer gas leakage rate over time; The battery leakage rate is obtained by using the leakage rate variation data. When the slope is 0≤k≤5E-09 and the time is ≥2s, the leakage rate with the largest absolute value in the leakage rate variation data is the battery leakage rate, wherein the slope k is calculated as follows: k = (y2-y1) / (x2-x1); In the formula, y1 is a first leakage rate, y2 is a second leakage rate adjacent to the first leakage rate, x1 is a time corresponding to the first leakage rate, and x2 is a time corresponding to the second leakage rate.

20. The battery airtightness detection method according to any one of claims 15 to 19, characterized in that: If the air pressure change value is less than a first threshold, injecting tracer gas into the battery cell through a tracer gas supply system comprises: If the air pressure change value is less than the first threshold value, the battery cell is evacuated by a vacuum pumping system until the vacuum degree of the battery cell is less than or equal to the second vacuum degree; A tracer gas is injected into the battery cell through a tracer gas supply system.

21. The battery airtightness detection method according to claim 20, characterized in that: The second vacuum degree is -95 kPa to -65 kPa.

22. The battery airtightness detection method according to any one of claims 15 to 21, characterized in that: After determining whether the leakage rate is qualified, the following steps are further included: The tracer gas within the battery cell is evacuated.

23. The battery airtightness detection method according to any one of claims 15 to 22, characterized in that: The step of determining whether the leakage rate is qualified also includes: removing the tracer gas from the sealed chamber; The sealed chamber is opened and the battery cell is taken out.

24. The battery airtightness detection method according to claim 23, characterized in that: The step of removing the tracer gas in the sealed chamber comprises: Residual gas in the sealed chamber is extracted until the vacuum degree in the sealed chamber is less than or equal to the third vacuum degree and the background value is less than or equal to the second threshold value.

25. The battery airtightness detection method according to claim 24, characterized in that: The third vacuum degree is -95 kPa, and the second threshold is 1E-07 Pa·m 3 / s.

Images