Battery airtightness detection device and method

Abstract

The invention is suitable for the technical field of power battery airtightness detection, and provides a battery airtightness detection device and method. The battery airtightness detection device comprises a sealed chamber, a vacuumizing pipeline and a gas injection pipeline, a plurality of sealing chambers are arranged; the sealing chamber is used for containing at least one battery monomer; a main body of the vacuumizing pipeline is located outside the sealed cavity, the vacuumizing pipeline is provided with a first gas port communicated with the sealed cavity, and the vacuumizing pipeline is used for communicating the sealed cavity with an external vacuumizing system and communicating the sealed cavity with an external mass spectrometer; a main body of the gas injection pipeline is located outside the sealing cavity, the gas injection pipeline is provided with a second gas port located in the sealing cavity, the second gas port is used for being communicated with the inner cavity of the battery monomer, and the gas injection pipeline is used for being communicated with the inner cavity of the battery monomer and an external tracing gas supply system. According to the battery airtightness detection device and method provided by the invention, the vacuumizing time can be shortened, and the difficulty of removing residual tracer gas can be reduced.

Description

Technical Field

[0001] 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

[0002] In the process of power battery production and manufacturing, the welding sealing performance of battery cells is closely related to the safety issues of their entire life cycle. Battery cells with poor airtightness have the 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 detection is particularly important. The current battery airtightness detection device and method have the problem of long vacuuming time. Summary of the invention

[0003] In view of the above problems, the present application provides 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.

[0004] 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.

[0005] The battery airtightness detection device is provided with a plurality of sealed chambers for containing at least one battery cell, and a vacuum extraction pipeline and a gas injection pipeline connected to the sealed chamber. This makes it unnecessary to place all the battery cells to be detected in the same batch in a large connected chamber for vacuum extraction and residual tracer gas removal when the battery cells are subjected to airtightness detection through an external vacuum extraction system and an external tracer gas supply system. Only the sealed chamber containing some battery cells needs to be vacuumed and residual tracer gas removed. This can reduce the time required for vacuum extraction to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers, 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 detection to a certain extent.

[0006] 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 at the opening of the cavity, and the side of the cover body facing the cavity and the inner walls of each of the sub-cavities enclose the sealed chamber; the vacuum pumping pipeline is arranged on the cover body or the cavity; and the gas injection pipeline is arranged on the cover body or the cavity. The sealed chamber is composed of the scheme provided in this embodiment, so that multiple sealed chambers can be assembled and transported as a whole, and the vacuum pumping pipeline, the gas injection pipeline and the sealed chamber can be combined into two parts, which is convenient for the assembly and disassembly of the battery airtightness detection device, and can make the structure of the entire battery airtightness detection device compact.

[0007] In some embodiments, the cavity includes: an outer shell having the opening; and a sub-shell disposed in the outer shell, the inner wall of the sub-shell surrounding the sub-cavity. By adopting the scheme provided in this embodiment, the outer shell and the sub-shell can be prepared separately and then assembled together, so that 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, which can expand the application scope of the outer shell in the battery airtightness detection device to a certain extent and reduce the cost required for battery airtightness 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.

[0008] In some embodiments, the sub-shell is detachably arranged in the outer shell. The solution provided by this embodiment is convenient for operators to replace the corresponding sub-shell according to the size of the battery monomer, and is also convenient for replacement of the sub-shell after damage, which can improve the convenience of using the battery airtightness detection device to a certain extent, and expand the application scope of the outer shell and sub-shell in the battery airtightness detection device, and reduce the cost required for battery airtightness detection.

[0009] In some embodiments, a sealing layer is provided between two adjacent sub-shells, and the sealing layer is in sealing contact with the cover body. The provision of the sealing layer can seal between the sub-shells and the cover body, and separate between two adjacent sub-cavities, reduce the mutual crosstalk of gases in the sub-cavities, and improve the accuracy of airtight detection.

[0010] In some embodiments, the sealing layer is disposed around the sub-shell, which can achieve a better sealing effect of the sealing layer.

[0011] In some embodiments, the sealing layer is an elastic layer; and / or the sealing layer is a rubber layer. The sealing layer is an elastic layer so that it can better seal with the cover body and improve the sealing effect. The sealing layer is a rubber layer, which is low in price and has a good sealing effect.

[0012] In some embodiments, 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 provided 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. The structure provided in this embodiment can make the contact area between the split shell and the cover body larger, and the sealing effect is better. At the same time, the first plug-in portion and the second plug-in portion can also reduce the risk of swelling and indentation of the battery cell during the injection of tracer gas during the airtightness test of the battery cell to a certain extent.

[0013] In some embodiments, two first plug-in parts 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.

[0014] In some embodiments, the first plug-in portion and the split shell are integrally formed, so that the connection between the first plug-in portion and the split shell is stable and easy to manufacture.

[0015] In some embodiments, the cover body includes: a cover body, which is sealed at the opening of the cavity; and a cover split body, which is arranged on one side of the cover body facing the cavity, and the cover split body is correspondingly sealed at the opening of the sub-cavity, and forms the sealed cavity with the inner wall of the sub-cavity. The cover body adopts the structure provided by this embodiment, so that the cover body and the cover split body can be prepared separately and then assembled together, so that the same cover body can be installed with the same specification of cover split bodies or different specifications of cover split bodies according to the use needs, which can expand the application scope of the cover body in the battery airtightness detection device to a certain extent and reduce the cost required for battery airtightness detection. And when the cover body and the cover split body are made of different materials, the production cost of the cavity can be reduced to a certain extent. In addition, if the cover body adopts the cover body of the cavity for holding multiple battery cells in the related art, the setting of the cover split body can fill a part of the space of the cavity, so that after the battery cell is placed in the shell, the residual space between the inner wall of the space surrounded by the shell and the cover body is small, which can shorten the vacuum time to a certain extent.

[0016] In some embodiments, the cover body is detachably mounted on a side of the cover body facing the cavity. The solution provided by 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.

[0017] 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 makes the structure of the cover body and the cover body simple, and facilitates the assembly or separation operation of the cover body and the cover body.

[0018] 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. In this way, 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 large enough, 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.

[0019] In a second aspect, a battery airtightness detection method is provided, which is based on a battery airtightness detection device provided by any of the above embodiments, comprising: evacuating a plurality of the sealed chambers until the vacuum degree in the sealed chambers 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.

[0020] The battery airtightness detection method provided in the embodiment of the present application adopts the battery airtightness detection device provided in the above embodiments, which can reduce the time required for vacuuming to a certain extent, and the tracer gas will not contaminate the adjacent sealed chambers, 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 detection to a certain extent. At the same time, first perform a large leak detection, that is, determine whether the air pressure change value is less than the first threshold value, and then perform a tracer gas leakage rate detection, which can reduce the risk of severe contamination caused by a large amount of tracer gas entering the sealed chamber, vacuum pipeline, etc. to a certain extent.

[0021] In some embodiments, the first threshold is 1 kPa. The first threshold adopts the value provided in this embodiment, the detection requirement meets the national standard, and the detection accuracy is high.

[0022] 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.

[0023] In some embodiments, the tracer gas includes helium or hydrogen. The tracer gas adopts the scheme provided in this embodiment, which is easy to obtain and will not cause pollution or adverse effects on the battery cells.

[0024] In some embodiments, the detecting the leakage rate of the battery cell comprises: extracting the tracer gas in the sealed chamber by a mass spectrometer to obtain the leakage rate variation data of the tracer gas over time; obtaining the battery leakage rate by the leakage rate variation data over time, and 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, wherein the slope k is calculated as follows: k=(y 2 -y 1 ) / (x 2 -x 1 );where y 1 is the first leakage rate, y 2 is the second leak rate adjacent to the first leak rate, x 1 is the time corresponding to the first leakage rate, x 2 The solution provided in this embodiment can shorten the operation time of step S5 to a certain extent and improve the efficiency of airtight detection.

[0025] In some embodiments, if the air pressure change value is less than the first threshold, injecting the tracer gas into the battery cell through the tracer gas supply system includes: if the air pressure change value is less than the first threshold, evacuating 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; injecting the tracer gas into the battery cell through the tracer gas supply system. In this way, the airtightness detection result can be accurate.

[0026] 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.

[0027] 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.

[0028] In some embodiments, after determining whether the leakage rate is qualified, the method further includes: removing the tracer gas in the sealed chamber; opening the sealed chamber and taking out the battery cell. In this way, the tracer gas can be removed in a smaller residual space, making it easier to remove the residual gas, so that the detection environment can maintain a qualified background value and reduce the impact of environmental noise.

[0029] In some embodiments, the clearing of the tracer gas in the sealed chamber includes: extracting the residual gas in the sealed chamber until the vacuum degree in the sealed chamber is less than or equal to a third vacuum degree and the background value is less than or equal to a second threshold value, so as to reduce the pollution of the tracer gas to the environment.

[0030] In some embodiments, the third vacuum degree 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.

[0031] 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

[0032] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0033] Figure 1 A schematic cross-sectional view of a battery airtightness detection device according to some embodiments of the present application;

[0034] Figure 2 A schematic diagram of the cross-sectional structure of a cavity and a cover in a battery airtightness detection device in some embodiments of the present application;

[0035] Figure 3 Schematic diagram of the exploded structure of a battery airtightness detection device according to some other embodiments of the present application;

[0036] Figure 4 Schematic diagram of the cross-sectional structure of the cavity and the cover in the battery airtightness detection device in other embodiments of the present application;

[0037] Figure 5 A schematic diagram of the explosion structure of the separate shell and cover in the battery airtightness detection device in some embodiments of the present application;

[0038] Figure 6 Schematic diagram of the cross-sectional structure of a battery airtightness detection device according to some other embodiments of the present application;

[0039] Figure 7 It is a bottom view structural schematic diagram of a cover body in a battery airtightness detection device in some embodiments of the present application;

[0040] Figure 8 This is a bottom view structural diagram of a cover body in a battery airtightness detection device according to some embodiments of the present application;

[0041] Fig. 9 A schematic diagram of a flow chart of a battery airtightness detection method according to some embodiments of the present application;

[0042] Fig.10 This is a flow chart of step S5 in the battery airtightness detection method in some embodiments of the present application;

[0043] Fig.11 This is a flow chart of step S4 in the battery airtightness detection method in some embodiments of the present application;

[0044] Fig.12 A schematic diagram of a flow chart of a battery airtightness detection method according to other embodiments of the present application;

[0045] Fig.13 A schematic diagram of a flow chart of a battery airtightness detection method according to other embodiments of the present application;

[0046] Fig.14 It is a schematic diagram of the structure of a battery cell;

[0047] Fig.15 The leakage rate variation curves corresponding to samples 1 to 6 are as a function of time.

[0048] The reference numerals in the specific implementation manner are as follows:

[0049] 10. Battery cell; 11. Large surface; 12. Side surface; 13. Top cover surface; 14. Explosion-proof disk; 15. Liquid injection hole; 16. Pole;

[0050] 100, sealed chamber; 200, vacuum pipeline; 210, first gas port; 300, gas injection pipeline; 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 split body; 540, installation groove. DETAILED DESCRIPTION

[0051] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field 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" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0053] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0054] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0055] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0056] 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).

[0057] 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. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0058] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0059] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0060] In the process of power battery production and manufacturing, the welding sealing performance of battery cells is closely related to their safety issues throughout their life cycle. Battery cells with poor airtightness have the 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 detection is particularly important. The battery airtightness detection 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 detection equipment usually places several battery cells in the same cavity for detection. During the detection, it is necessary to first evacuate the entire cavity for a large leak detection, and then inject the tracer gas into the battery cell. By detecting the leakage rate of the tracer gas, it is determined whether the battery cell has a leak. When any of the above two steps measures a leakage rate exceeding 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 the volume of a single battery cell is generally large, the volume of the cavity for placing several battery cells is large, which results in a long vacuum time when the airtightness test of the battery cells is performed by 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.

[0061] 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 a plurality of sealed chambers for containing at least one battery cell, and a vacuum extraction 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 extraction and residual tracer gas removal when the battery cells are subjected to airtightness detection through an external vacuum extraction system and an external tracer gas supply system. Only the sealed chamber containing some battery cells needs to be vacuumed and residual tracer gas removed. This can reduce the time required for vacuum extraction to a certain extent, and the tracer gas will not contaminate adjacent sealed chambers. This 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 detection to a certain extent.

[0062] 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.

[0063] The battery production line generally includes a battery production system and a battery testing system. The battery testing system includes the above-mentioned battery airtightness testing device. In addition, the battery testing system may also include size testing equipment, etc., which can be determined according to the testing needs and is not limited here.

[0064] Please refer to Figure 1 As shown, the battery airtightness detection device provided in the embodiment of the present application includes a sealing chamber 100 , a vacuum pumping pipeline 200 and a gas injection pipeline 300 .

[0065] There are a plurality of sealed chambers 100 , each of which is used to contain at least one battery cell 10 .

[0066] The main body of the vacuum pumping pipeline 200 is located outside the sealed chamber 100. The vacuum pumping pipeline 200 has a first gas port 210 communicating with the sealed chamber 100. The vacuum pumping pipeline 200 is used to connect the sealed chamber 100 with an external vacuum pumping system and connect the sealed chamber 100 with an external mass spectrometer.

[0067] 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.

[0068] It should be noted that the sealed chamber 100 in this embodiment is not an integrally formed structure, but is composed of multiple parts, and can be opened to place the battery cell 10, or to 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 may be the same or different, depending on 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, depending on the needs of use.

[0069] The vacuum line 200 has at least a first gas port 210 and a connecting port connected to an external vacuum system and an external mass spectrometer, which can be an integrally formed structure, or can be composed of a plurality of tubes and / or connectors, which can be determined according to the use needs. It is understandable that the above-mentioned connecting port can be one or two. When the connecting port is one, a tee can be installed in the connecting port to realize the simultaneous connection of the vacuum line 200 with the external vacuum system and the external mass spectrometer. In addition, the part where the tee is 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 use needs. 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.

[0070] The gas injection pipeline 300 has at least a second gas port 310 and a connecting port connected to an external tracer gas supply system, which can be an integrally formed structure or a combination of multiple pipe bodies and / or connectors, which can be determined according to the use requirements. It should be noted that an on-off valve is generally provided at the second gas port 310 or at the branch where the main pipeline of the gas injection pipeline 300 is connected to the second gas port 310, that is, the multiple second gas ports 310 can be connected or disconnected with the main pipeline of the gas injection pipeline 300 by connecting or blocking the on-off valve.

[0071] The number of the first gas ports 210 and the second gas ports 310 is generally consistent with the number of the sealed chambers 100 .

[0072] The principle of using the battery airtightness detection device provided in this embodiment to perform battery airtightness detection is as follows:

[0073] Before testing, multiple battery cells 10 to be tested in the same batch are placed in multiple sealed chambers 100, the vacuum line 200 is connected to the external vacuum system, and the gas injection line 300 is connected to the external tracer gas supply system. The battery cell 10 is provided with a detection element for detecting the internal pressure thereof, and the detection element can transmit the detection signal to the control device located outside the sealed chamber 100 through an electrical connector or a wireless transmission module.

[0074] Then, a major leak test is performed. When performing a major leak test, the vacuum system is first started, and the sealed chamber 100 is evacuated through the vacuum system and the vacuum pipeline 200. The control device receives the data transmitted by the detection element in the battery cell 10, and determines whether the air pressure change in the battery cell 10 meets the test requirements within a preset time period. If not, it is determined that the airtightness of the corresponding battery cell 10 does not meet the requirements, and the test is terminated.

[0075] 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 a preset time period is less than a preset threshold value. If it is less than the preset threshold value, 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 value, 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.

[0076] 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, and then the sealed chamber 100 is opened to take out the battery cell 10 therein.

[0077] The battery airtightness detection device provided in the embodiment of the present application is provided with a plurality of sealed chambers 100 for containing at least one battery cell 10, and a vacuum extraction pipeline 200 and a gas injection pipeline 300 connected to the sealed chamber 100. This makes it unnecessary to place all the battery cells tested in the same batch in a large connected chamber for vacuum extraction and residual tracer gas removal when the battery cells 10 are subjected to airtightness detection through an external vacuum extraction system and an external tracer gas supply system. It is only necessary to vacuum extract and remove the residual tracer gas from the sealed chamber 100 containing some of the battery cells 10. In this way, the residual space between the battery cell 10 and the sealed chamber 100 is small after the battery cell 10 is placed therein, which can reduce the time required for vacuum extraction to a certain extent, and the tracer gas will not contaminate the adjacent sealed chamber 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 the battery airtightness detection to a certain extent.

[0078] like Figure 1 and Figure 2 As shown, 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 is sealed at the opening of the cavity 400. The side of the cover 500 facing the cavity 400 and the inner wall 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.

[0079] The cavity 400 in this embodiment may adopt an integrally formed structure, or may adopt a split structure in which a large cavity 400 is provided with a plurality of sub-cavities for containing at least one battery cell, and the specific structure may be determined according to the use requirements.

[0080] 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.

[0081] The cover body 500 may be an integrally formed structure or a split structure composed of multiple components, which may be determined according to usage requirements.

[0082] 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 pipeline 200, the gas injection pipeline 300 and the sealed chamber 100 can be combined into two parts, which is convenient for the assembly and disassembly of the battery airtight detection device and can make the structure of the entire battery airtight detection device compact.

[0083] In some embodiments, Figure 2 and Figure 3 As shown, 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 inside the outer shell 420, and the inner wall of the sub-shell 430 surrounds the sub-cavity 410.

[0084] The housing 420 is generally formed in one piece and has a large inner cavity capable of containing a plurality of sub-shells 430. The housing 420 in this embodiment may be a cavity 400 for containing a plurality of battery cells 10 in the aforementioned related art.

[0085] 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.

[0086] The materials of the sub-shell 430 and the outer shell 420 may be the same or different, depending on the specific usage requirements.

[0087] By adopting the scheme provided in this embodiment, the outer shell 420 and the sub-shell 430 can be prepared separately and then assembled together, so that the sub-shell 430 of the same specification or the sub-shell 430 of different specifications can be installed in the same outer shell 420 according to the use requirements, which can expand the application scope of the outer shell 420 in the battery airtightness detection device to a certain extent and reduce the cost required for battery airtightness detection. And 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 for holding multiple battery cells 10 in the related art, the setting of the sub-shell 430 can fill a part of the space of 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.

[0088] In some embodiments, the sub-shell 430 can be detachably disposed in the outer shell 420 .

[0089] Separably arranged in the housing 420 means that the sub-housing 430 can be taken out of the housing 420 according to the use needs after being installed in the housing 420. For example, the sub-housing 430 can be detachably arranged in the housing 420 by plugging, snapping, directly placing, etc.

[0090] The solution provided in this embodiment makes it convenient 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 air-tightness detection device to a certain extent, expand the scope of application of the outer shell 420 and the sub-shells 430 in the battery air-tightness detection device, and reduce the cost required for battery air-tightness detection.

[0091] In some embodiments, Figure 4 As shown, a sealing layer 450 is disposed between two adjacent sub-shells 430 , and the sealing layer 450 is in sealing contact with the cover body 500 .

[0092] The sealing layer 450 is a layer structure capable of performing a sealing effect.

[0093] The provision of the sealing layer 450 can ensure the sealing between the sub-shell 430 and the cover body 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 airtightness detection.

[0094] In some embodiments, the sealing layer 450 is disposed around the sub-shell 430. This can provide a better sealing effect of the sealing layer 450.

[0095] In some embodiments, the sealing layer 450 is an elastic layer. The elastic layer means that the sealing layer 450 can be deformed after being subjected to an external force, and can return to its original shape after the external force is removed. The use of an elastic layer for the sealing layer 450 can better seal with the cover 500 and improve the sealing effect.

[0096] 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 a rubber layer, which is low in price and has a good sealing effect.

[0097] In some embodiments, Figure 5 As shown, the first plug-in portion 440 is provided on one side of the split shell 430 facing the cover 500 . The second plug-in portion 510 corresponding to the first plug-in portion 440 is provided on one side of the cover 500 facing the cavity 400 . The second plug-in portion 510 is sealed and plugged with the first plug-in portion 440 .

[0098] The first plug-in portion 440 may 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 may be an independent component prepared separately from the split shell 430, and fixed to the split shell 430 by welding, bonding, detachable connection, etc. One or more first plug-in portions 440 may be provided, which may be a protrusion, such as a convex column, a bump, etc., or a concave portion, such as a groove, a blind hole, etc.

[0099] 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 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 consistent with the number of the first plug-in portions 440, and the shape and portion of the second plug-in portion 510 can be determined according to the shape and portion of the first plug-in portion 440. If the first plug-in portion 440 is a convex portion, the second plug-in portion 510 is a concave portion, and if the first plug-in portion 440 is a concave portion, the second plug-in portion 510 is a convex portion.

[0100] By adopting the structure provided in this embodiment, the contact area between the split shell 430 and the cover 500 can be larger, and the sealing effect can be better. At the same time, 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 to a certain extent.

[0101] 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 the forces on both sides of the split shell 430 to be balanced.

[0102] In some embodiments, the first plug-in portion 440 is a protruding portion, and the second plug-in portion 510 is a recessed portion.

[0103] In this way, the volume and weight of the cover body 500 can be reduced, and it is convenient to separate the cover body 500 from the cavity 400 and to seal the cover body 500 on the cavity 400 .

[0104] In some embodiments, the first plug-in portion 440 is integrally formed with the split shell 430. This can stabilize the connection between the first plug-in portion 440 and the split shell 430 and facilitate preparation.

[0105] In some embodiments, the sub-shell 430 is a stainless steel member or a Teflon member.

[0106] The split shell 430 is made of stainless steel, which has good corrosion resistance, high hardness, good structural stability and long service life.

[0107] 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, insulation, etc. It has good structural stability and a long service life.

[0108] In some embodiments, Figure 6 As shown, the cover body 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 a side of the cover body 520 facing the cavity 400. The cover body 530 seals the opening of the sub-cavity 410 and forms a sealed chamber 100 with the inner wall of the sub-cavity 410.

[0109] The cover body 520 may be an integrally formed structural member or a combination of multiple components. The cover body 520 in this embodiment may adopt the cover body 500 in the cavity 400 for placing multiple battery cells 10 in the aforementioned related art.

[0110] The number of the cover parts 530 is generally consistent with 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.

[0111] The cover body 500 adopts the structure provided by this embodiment, so that the cover body 520 and the cover split body 530 can be prepared separately and then assembled together. In this way, the cover split body 530 of the same specification or the cover split body 530 of different specifications can be installed on the same cover body 520 according to the use requirements, which can expand the application scope of the cover body 520 in the battery airtightness detection device to a certain extent and reduce the cost required for battery airtightness detection. And when the cover body 520 and the cover split body 530 are made of different materials, the production cost of the cavity 400 can be reduced to a certain extent. In addition, if the cover body 520 adopts the cover body 500 of the cavity 400 used for holding multiple battery cells 10 in the related art, the setting of the cover split body 530 can fill a part of the space of the cavity 400, so that after the battery cell 10 is placed in the shell 420, the residual space between the inner wall of the space surrounded by the shell 420 and the cover body 500 is small, which can shorten the vacuuming time to a certain extent.

[0112] In some embodiments, Figure 7 and Figure 8 As shown, the cover body 530 is detachably mounted on a side of the cover body 520 facing the cavity 400 .

[0113] 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 plug-in or snap-in, and the structures of the cover body 520 and the cover body 530 will not be damaged during disassembly.

[0114] 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.

[0115] In some embodiments, Figure 7 and Figure 8 As shown, a mounting groove 540 is provided on a side of the cover body 520 facing the cavity 400 , and at least a portion of the cover split body 530 is inserted into the mounting groove 540 .

[0116] 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.

[0117] In some embodiments, the cover body 530 is a stainless steel member or a Teflon member.

[0118] The cover body 530 is made of stainless steel, which has good corrosion resistance, high hardness, good structural stability and long service life.

[0119] 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.

[0120] 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 .

[0121] 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 detection of the battery cell 10.

[0122] In some embodiments, a dimension of the sealed chamber 100 in at least one direction is 0.2 mm to 0.5 mm larger than a dimension of the battery cell 10 .

[0123] like Figure 1 As shown, in the X direction, the size of the battery cell 10 is a1, the size of the sealed chamber 100 is a2, and a2-a1 is 0.2mm-0.5mm. Figure 1 The X direction is the thickness direction of the battery cell. In other embodiments, the size of the sealed chamber 100 in other directions may be larger than the size of the battery cell 10, which may be determined according to the use requirements.

[0124] 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 detection of the battery cell 10.

[0125] According to some embodiments of the present application, the present application also provides a battery detection system, including the battery airtightness detection device provided by any of the above embodiments.

[0126] The battery detection system provided in the embodiment of the present application adopts the battery airtight detection 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 the adjacent sealed chambers, 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 airtight detection to a certain extent.

[0127] 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.

[0128] The battery production line provided in the embodiment of the present application adopts the battery airtightness detection 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 the adjacent sealed chambers, 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 detection to a certain extent.

[0129] According to some embodiments of the present application, Fig. 9 As shown, the present application also provides a battery airtightness detection method, including but not limited to the following steps:

[0130] S1. Evacuate multiple sealed chambers until the vacuum degree in the sealed chamber is less than or equal to a first vacuum degree, and each sealed chamber contains at least one battery cell.

[0131] The vacuum operation can be achieved through a vacuum system.

[0132] S2. Detect the change of air pressure in the battery cell and obtain the value of the air pressure change.

[0133] The air pressure change value in this step can be calculated using data obtained by an air pressure sensor disposed in the battery cell.

[0134] S3. Determine whether the air pressure change value is less than a first threshold.

[0135] The first threshold can be derived based on testing experience. The first threshold is a threshold that can determine whether there is a leak in the battery cell. If the air pressure change value is greater than or equal to the first threshold, it can be directly determined that the battery cell has a leak and is a defective product. If the air pressure change value is less than the first threshold, further testing is required to determine whether the battery cell is a qualified product.

[0136] S4. If the air pressure change value is less than the first threshold value, inject tracer gas into the battery cell through the tracer gas supply system.

[0137] The injection of tracer gas can be achieved through a tracer gas supply system and a gas injection pipeline.

[0138] S5. Detect the leakage rate of the battery cells.

[0139] 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 amount of tracer gas in the gas over time.

[0140] S6. Determine whether the leakage rate is qualified.

[0141] If the leakage rate is less than the preset range value, it is considered that the leakage rate is qualified, and the corresponding battery monomer is judged to meet the air tightness requirements and is a qualified product. If the leakage rate is greater than or equal to the preset range value, it is considered that the leakage rate is unqualified, and the corresponding battery monomer is judged to have a leakage point and is a defective product.

[0142] The battery airtightness detection method provided in the embodiment of the present application adopts the battery airtightness detection device provided in the above embodiments, which can reduce the time required for vacuuming to a certain extent, and the tracer gas will not contaminate the adjacent sealed chambers, 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 detection to a certain extent. At the same time, first perform a large leak detection, that is, determine whether the air pressure change value is less than the first threshold value, and then perform a tracer gas leakage rate detection, which can reduce the risk of severe contamination caused by a large amount of tracer gas entering the sealed chamber, vacuum pipeline, etc. to a certain extent.

[0143] In some embodiments, the first threshold is 1 kPa.

[0144] 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.

[0145] 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 value provided in this embodiment, which can meet the detection requirements and requires less energy consumption.

[0146] 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 includes 3% to 5.5% hydrogen and 94.5% to 97% nitrogen, and the sum of the volume fractions of hydrogen and nitrogen is 100%. The tracer gas adopts the scheme provided in this embodiment, which is convenient for material collection and will not cause pollution or adverse effects on the battery monomer.

[0147] In some embodiments, Fig.10 As shown, step S5 of detecting the leakage rate of the battery cell 10 includes but is not limited to the following steps:

[0148] S51 . Extracting tracer gas in the sealed chamber 100 through a mass spectrometer to obtain data on the variation of the leakage rate of the tracer gas over time.

[0149] The above-mentioned leak rate variation data over time can be directly generated by a mass spectrometer, or can be obtained by observing the total amount of tracer gas extracted by the mass spectrometer at different times through relevant calculations, and there is no sole limitation here. The leak rate variation data over time is generally a one-to-one correspondence data between the detection time and the leak rate.

[0150] The above 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., such as Fig.15 As shown, the specific configuration can be determined based on usage requirements.

[0151] S52. Obtain the battery leakage rate through 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, wherein the slope k is calculated as follows:

[0152] k=(y 2 -y 1 ) / (x 2 -x 1 );

[0153] In the formula, y 1 is the first leakage rate, y 2 is the second leak rate adjacent to the first leak rate, x 1 is the time corresponding to the first leakage rate, x 2 is the time corresponding to the second leak rate.

[0154] 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.

[0155] 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 airtight detection.

[0156] In some embodiments, Fig.11 As shown, step S4 includes:

[0157] S41, if the air pressure change value is less than the first threshold value, evacuate 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;

[0158] S42, injecting tracer gas into the battery cell through the tracer gas supply system.

[0159] This can make the airtightness test results accurate.

[0160] 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.

[0161] In some embodiments, Fig.12 As shown, after step S6 determines whether the leakage rate is qualified, it also includes:

[0162] S7. Evacuate the tracer gas in the battery cell.

[0163] This operation can be achieved through the gas injection pipeline and an external tracer gas supply system, or by connecting the gas injection pipeline with an external vacuum system, or by connecting the gas injection pipeline with other exhaust systems, depending on the specific needs.

[0164] Evacuating the tracer gas in the battery cell can, to a certain extent, prevent the tracer gas inside the battery cell from continuously leaking into the sealed chamber.

[0165] In some embodiments, Fig.13 As shown, after step S6 determines whether the leakage rate is qualified, it also includes:

[0166] S8. Clear the tracer gas in the sealed chamber.

[0167] This operation can be achieved through a vacuum pumping pipeline and an external vacuum pumping system, through a vacuum pumping pipeline and a mass spectrometer, or through the vacuum pumping pipeline connected to other exhaust systems, depending on the specific needs.

[0168] S9. Open the sealed chamber and take out the battery cell. The closed chamber is used to extract the tracer gas in the sealed chamber, so that the tracer gas can be removed in a smaller residual space, making it easier to remove the residual gas, so that the detection environment can maintain a qualified background value and reduce the impact of environmental noise. The above background value refers to the signal value of the detector (such as an external mass spectrometer) when there is no sample injection. It is related to the type of detector and is a value that cannot be removed in any way.

[0169] In some embodiments, step S8, clearing the tracer gas in the sealed chamber, includes but is not limited to the following steps:

[0170] 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.

[0171] This can reduce the pollution of tracer gas to the environment.

[0172] In some embodiments, the third vacuum degree is -95 kPa, and the second threshold is 1E-07 Pa·m 3 / s.

[0173] 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.

[0174] According to some embodiments of the present application, Figures 1 to 8 As shown, a battery airtightness detection device is provided, which includes a sealed chamber 100 , a vacuum pumping pipeline 200 and a gas injection pipeline 300 .

[0175] There are a plurality of sealed chambers 100 . Each sealed chamber 100 is surrounded by at least two parts, and the sealed chamber is used to contain at least one battery cell 10 .

[0176] The main body of the vacuum pumping pipeline 200 is located outside the sealed chamber 100. The vacuum pumping pipeline 200 has a first gas port 210 communicating with the sealed chamber 100. The vacuum pumping pipeline 200 is used to connect the sealed chamber 100 with an external vacuum pumping system and connect the sealed chamber 100 with an external mass spectrometer.

[0177] 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.

[0178] 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 split 530. The cover body 520 is sealed at the opening of the cavity 400. A mounting groove is provided on one side of the cover body 520 facing the cavity 400, and at least part of the cover split 530 is inserted into the mounting groove. The cover split 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 split 530 is a stainless steel part or a Teflon part.

[0179] A sealing layer 450 is disposed between two adjacent sub-shells 430, and the sealing layer 450 is in sealing contact with the cover body 500. The sealing layer 450 is disposed around the sub-shells 430. In this way, the sealing effect of the sealing layer 450 can be better. The sealing layer 450 is a rubber layer.

[0180] The side of the sub-shell 430 facing the cover 500 is provided with a convex part. The side of the cover 500 facing the cavity 400 is provided with a concave part corresponding to the first plug-in part 440, and the concave part is sealed and plugged with the convex part. The sub-shell 430 is a stainless steel part or a Teflon part.

[0181] The battery airtightness detection device provided in this embodiment adopts a sub-chamber 410 design for a large chamber originally used to place multiple battery cells 10. The sub-chamber 410 reduces the residual space between the battery cell 10 and the sealed chamber 100 by arranging filling blocks such as a sub-shell 430 and a cover sub-body 530 in the above-mentioned large chamber.

[0182] When testing the air tightness of the battery cell 10, the battery cell 10 can be first clamped by a robot and placed in the cavity 400. At this time, the cavity 400 and the cover 500 are as shown in FIG. Figure 3 As shown in the separated state, the cavity 400 is then lifted upward to close the cavity 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 through the pump, evacuation pipeline and vacuum pipeline in the vacuum system to perform a major leak detection. When performing a major leak detection, 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, the battery cell has a leak point and is a defective product, and the detection is completed. If the air pressure change value is less than the first threshold, the next step of detection is performed.

[0183] Inject tracer gas into the battery cell 10 that has passed the above-mentioned large leak detection (i.e., the battery cell 10 whose air pressure change value is less than the first threshold), and detect the leakage rate of the battery cell 10 by means of a mass spectrometer; if the leakage rate exceeds the specification, the battery cell has a leakage point and is a defective product, and the detection is completed. After that, the tracer gas in the battery cell is evacuated by means of a pump and an air injection pipeline, and the residual tracer gas in the sealed chamber is removed by means of a pump and a vacuum pipeline, and the tracer gas amount in the sealed chamber is detected by means of a mass spectrometer. If it meets the requirements, the sealed chamber is opened and the battery cell is taken out. If it does not meet the requirements, the residual tracer gas in the sealed chamber is removed by means of a pump and a vacuum pipeline, and the above operation is repeated. If the leakage rate detection is qualified, the battery cell is considered to be a qualified product.

[0184] 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 the residual tracer gas from contaminating adjacent divided chambers, and large leak detection effectively avoids severe contamination of the chamber. The closed chamber method for removing residual tracer gas is fast and efficient.

[0185] The above-mentioned sub-cavity design adopts one battery cell 10 corresponding to one sub-cavity 410, and the sub-shell 430 and the cover body 530 are designed to complement each other. The limiting dimensions of the side 12, large surface 11 and top cover surface 13 of the battery cell 10 are 0.2mm~0.5mm, that is, the dimensions of the side, large surface and top cover surface of the above-mentioned sealed chamber 100 are 0.2mm~0.5mm larger than the dimensions of the corresponding surfaces of the battery cell 10. Please refer to Figure 1 and Fig.14 In some embodiments, the side surface of the sealed chamber 100 is 0.4 mm larger than the side surface 12 of the battery cell 10, and the top surface is 0.2 mm larger than the top cover surface 13 of the battery cell 10 to avoid crushing the structures on the battery cell, such as the pole 15.

[0186] The above-mentioned large leak detection principle is that the sealed chamber 100 is vacuumed first. If there is a large leakage hole in the battery cell 10, the gas pressure inside the battery cell 10 will be significantly reduced; wherein 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 the battery cell 10 has a large leakage hole, that is, there is a large leak.

[0187] The above-mentioned tracer gas is one of helium or hydrogen, wherein the purity of the injected helium gas is 99.999%, 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%.

[0188] In the above operation process, before injecting the tracer gas into the battery cell 10 , it is necessary to evacuate the gas in the battery cell 10 , and the evacuation pressure of the battery cell 10 is -95 kPa to -65 kPa.

[0189] 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.

[0190] The injecting of tracer gas into the battery cell 10 that has passed the major leak detection (ie, the battery cell 10 whose gas pressure change value is less than the first threshold) is to inject the tracer gas into the battery cell 10 through the gas injection pipeline 300 and the liquid injection hole 15 on the battery cell 10 .

[0191] The specific operation of detecting the leakage rate of the battery cell 10 by the mass spectrometer is as follows:

[0192] In the process of detecting tracer gas leakage, the battery leakage rate is obtained through the data of 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, where the slope k is calculated as follows:

[0193] k=(y 2 -y 1 ) / (x 2 -x 1 );

[0194] In the formula, y 1 is the first leakage rate, y 2 is the second leak rate adjacent to the first leak rate, x 1 is the time corresponding to the first leakage rate, x 2 is the time corresponding to the second leak rate.

[0195] 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.

[0196] For ease of understanding, we used 6 samples for testing, as shown in the attached Fig.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.

[0197] 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 airtight detection is shown in the following table:

[0198]

[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 extracting residual gas is fast and efficient, saving more than 90% of the time required for 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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, it includes: Sealed chambers, with multiple provided; the sealed chambers are 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 communicating with 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; And An air injection pipeline, the main body of the air injection pipeline is located outside the sealed chamber, the air injection pipeline has a second air port located inside the sealed chamber, the second air port is used to communicate with the inner cavity of the battery cell, and the air injection pipeline is used to connect the inner cavity of the battery cell 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 further includes: A cavity, having an opening and provided with multiple sub-cavities inside; and A cover body, covering the opening of the cavity, and a surface of the cover body facing the cavity and the inner walls of the respective sub-cavities enclose the sealed chamber; The vacuum pumping pipeline is provided on the cover body or the cavity; the air injection pipeline is provided on the cover body or the cavity.

3. The battery airtightness detection device according to claim 2, characterized in that, The cavity includes: A housing, having the opening; and A sub-housing, provided inside the housing, and the inner wall of the sub-housing encloses the sub-cavity.

4. The battery airtightness detection device according to claim 3, characterized in that, The sub-housing is detachably provided inside the housing.

5. The battery airtightness detection device according to claim 3 or 4, characterized in that, A sealing layer is provided between two adjacent sub-housings, 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-housing.

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 3-7, characterized in that, A first insertion part is provided on a surface of the sub-housing facing the cover body; A second insertion part corresponding to the first insertion part is provided on a surface of the cover body facing the cavity, and the second insertion part is in sealing insertion with the first insertion part.

9. The battery airtightness detection device according to claim 8, characterized in that, There are two first insertion parts and they are respectively arranged on two opposite side walls of the sub-housing.

10. The battery airtightness detection device according to claim 8 or 9, characterized in that, The first insertion part is integrally formed with the sub-housing.

11. The battery airtightness detection device according to any one of claims 2-10, characterized in that, The cover body includes: A cover main body, covering the opening of the cavity; and A cover sub-body, provided on a surface of the cover main body facing the cavity, the cover sub-body correspondingly covers the opening of the sub-cavity, and the cover sub-body and the inner wall of the sub-cavity enclose the sealed chamber.

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

13. The battery airtightness detection device according to claim 12, It is characterized in that an installation groove is provided on one side of the cover body facing the cavity, and at least a part of the cover is inserted into the installation groove.

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

15. A battery airtightness detection method based on the battery airtightness detection device according to any one of claims 1-14, It is characterized in that including: Vacuumizing a plurality of the sealing chambers until the vacuum degree in the sealing chambers is less than or equal to the first vacuum degree, and at least one battery cell is placed in each sealing chamber; 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 the first threshold; If the air pressure change value is less than the first threshold, injecting a tracer gas into the battery cell through a tracer gas supply system; Detecting the leakage rate of the battery cell; Judging whether the leakage rate is qualified.

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

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

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

19. The battery airtightness detection method according to claim 15, It is characterized in that the detecting the leakage rate of the battery cell includes: Extracting the tracer gas in the sealing chamber through a mass spectrometer to obtain the data of the leakage rate of the tracer gas changing with time; Obtaining the battery leakage rate from the data of the leakage rate changing with time. When the slope 0 ≤ k ≤ 5E-09 and the time ≥ 2 s, the maximum absolute value of the leakage rate in the data of the leakage rate changing with time is the battery leakage rate, where the calculation method of the slope k is: k = (y 2 - y 1 ) / (x 2 - x 1 ); where y 1 is the first leak rate, y 2 is the second leak rate adjacent to the first leak rate, x 1 is the time corresponding to the first leak rate, x 2 is the time corresponding to the second leak rate.

20. The battery airtightness detection method according to any one of claims 15-19, It is characterized in that the if the air pressure change value is less than the first threshold, injecting a tracer gas into the battery cell through a tracer gas supply system includes: If the air pressure change value is less than the first threshold, evacuating the battery cell through a vacuum system until the vacuum degree of the battery cell is less than or equal to the second vacuum degree; Injecting a tracer gas into the battery cell through a tracer gas supply system.

21. The battery airtightness detection method according to claim 20, It is 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 15-21, It is characterized in that after judging whether the leakage rate is qualified, it further includes: Evacuating the tracer gas in the battery cell.

23. The battery airtightness detection method according to any one of claims 15-22, It is characterized in that After determining whether the leakage rate is qualified, the following steps are further included: Remove the tracer gas in the sealed chamber; Open the sealed chamber and take out the battery cell.

24. The battery airtightness detection method according to claim 23, characterized in that The removing the tracer gas in the sealed chamber includes: Extract the residual gas in the sealed chamber 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.

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