Battery cell leakage detection system

Abstract

This application provides a battery cell leakage detection system, comprising: a vacuum system; a first chamber for placing the battery cell to be tested; a first branch connecting the vacuum system and the first chamber, wherein a first valve group is connected to the first branch for controlling the on / off state of the first branch; and a second branch connecting the vacuum system and the first chamber, wherein a second chamber and a second valve group are connected to the second branch for controlling the on / off state of the second branch. A leakage detector is installed inside the second chamber. The battery cell leakage detection system provided by this application has a simple structure, is easy to manufacture, has strong stability, and good detection effect, effectively avoiding over-detection and under-detection problems in battery cell leakage detection.

Description

Technical Field

[0001] This application relates to the field of battery cell testing technology, and in particular to a battery cell leakage detection system. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density and excellent cycle performance, and are widely used in power, energy storage devices, and 3C products for charging and discharging. The battery cell is the core energy storage unit of a lithium-ion battery, and its internal structure utilizes Li / Li... + Electrochemical redox reactions convert chemical energy into electrical energy. Ion migration at the solid-liquid interface is crucial during this conversion, and this migration relies on the electrolyte. Electrolyte leakage can have serious consequences, necessitating leakage detection of the battery cells. Existing leakage detection systems often suffer from either missed detections or over-detections; therefore, a more effective battery cell leakage detection system is urgently needed. Utility Model Content

[0003] In view of this, the purpose of this application is to provide a battery cell leakage detection system to solve the related problems mentioned in the background art.

[0004] This application provides a battery cell leakage detection system, comprising: a vacuum system; a first chamber for placing the battery cell to be tested; a first branch connected between the vacuum system and the first chamber, wherein a first valve group is connected to the first branch for controlling the on / off state of the first branch; a second branch connected between the vacuum system and the first chamber, wherein a second chamber and a second valve group are connected to the second branch for controlling the on / off state of the second branch; and a leakage detector is provided inside the second chamber.

[0005] Furthermore, the second valve assembly includes a first connecting valve and a second connecting valve, wherein the first connecting valve is connected between the second chamber and the first chamber, and the second connecting valve is connected between the second chamber and the air extraction system.

[0006] Furthermore, a third chamber is connected to the first branch, and a filter element is provided in the third chamber. The filter element is used to filter the gas drawn from the first chamber by the air extraction system.

[0007] Furthermore, the first valve assembly includes a third connecting valve and a fourth connecting valve, the third connecting valve being connected between the third chamber and the first chamber, and the fourth connecting valve being connected between the third chamber and the air extraction system.

[0008] Furthermore, both the second chamber and the third chamber are columnar chambers, the leakage detector is located in the center of the second chamber, and the filter element is an adsorption filter element.

[0009] Furthermore, the pumping system includes two vacuum pumps, one of which is connected to the first branch and the other of which is connected to the second branch.

[0010] Furthermore, the first chamber is connected to a pressure relief valve, which is used to control the connection between the first chamber and the external environment.

[0011] Furthermore, a camera is provided in the first chamber, and the camera is used to collect image information of the battery cell.

[0012] Furthermore, the first chamber includes a mating cavity and a cavity cover, the cavity cover being driven by a drive device, the drive device being used to control the opening and closing of the cavity cover; a moving platform is provided inside the first chamber, the moving platform being used to carry the battery cell and drive the battery cell to move.

[0013] Furthermore, the cell leakage detection system also includes a control unit, which is electrically connected to the drive device, the mobile platform, the air extraction system, the pressure relief valve, the first valve group, and the second valve group, respectively.

[0014] As described above, the battery cell leakage detection system provided in this application includes: a vacuum system; a first chamber for placing the battery cell to be tested; a first branch connected between the vacuum system and the first chamber, with a first valve group connected to the first branch for controlling the on / off state of the first branch; and a second branch connected between the vacuum system and the first chamber, with a second chamber and a second valve group connected to the second branch for controlling the on / off state of the second branch. A leakage detector is installed inside the second chamber. By setting up a first branch and a second branch in parallel between the vacuum system and the first chamber, with the battery cell placed in the first chamber and the leakage detector placed in the second chamber connected to the second branch, the battery cell and leakage detector can be relatively isolated, thus balancing the test pressure and providing a basis for improving the detection effect. The first branch connects to the first valve group, and the second branch connects to the second valve group. Before placing the battery cell, the first valve group is opened and the second valve group is closed. The evacuation system can evacuate the second chamber through the second branch, providing a reference for the leak detector. Then, the first valve group is closed and the second valve group is opened. After placing the battery cell, the evacuation system can evacuate the first chamber separately through the first branch, ensuring the stability of the vacuum level during subsequent testing. Finally, the first valve group is opened and the second valve group is closed. The leak detector can then perform leak detection on the battery cell in an environment without cold air disturbance and with a stable vacuum level, thus avoiding over-detection and under-detection issues. This battery cell leak detection system has a simple structure, is easy to manufacture, has strong stability, and good detection effect, effectively avoiding over-detection and under-detection problems in battery cell leak detection. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the module connection of a battery cell leakage detection system in an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of another battery cell leakage detection system in this application embodiment.

[0018] Figure 3 for Figure 2 A schematic diagram of the module connections for the cell leakage detection system.

[0019] Figure 4 This is a flowchart illustrating the process of leak detection for battery cells.

[0020] Reference numerals in the attached diagram: 1. Vacuum system; 2. First chamber; 2-1. Pressure relief valve; 2-2. Camera; 2-3. Chamber body; 2-4. Chamber cover; 2-5. Drive device; 2-6. Moving platform; 2-7. Battery cell; 3. First branch; 3-1. First valve group; 3-11. Third connecting valve; 3-12. Fourth connecting valve; 3-2. Third chamber; 3-3. Filter element; 4. Second branch; 4-1. Second chamber; 4-2. Second valve group; 4-21. First connecting valve; 4-22. Second connecting valve; 4-3. Leakage detector; 5. Control unit. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0022] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] Lithium-ion batteries possess advantages such as high energy density and excellent cycle performance, and are widely used in power, energy storage devices, and 3C products for charging and discharging. The battery cell is the core energy storage unit of a lithium-ion battery, and its internal structure utilizes Li / Li... + Electrochemical redox reactions enable the conversion of chemical energy into electrical energy.

[0024] During the conversion process, ion migration at the solid-liquid reaction interface is crucial, and this migration relies on the electrolyte. Currently, the organic electrolytes and negative electrodes in common battery cell systems are highly sensitive to moisture and air. When a charged battery cell is damaged and leaks electrolyte, it causes rapid oxidation of the negative electrode (Li), and electrolyte hydrolysis produces hydrogen fluoride, which damages the positive and negative electrode interfaces, leading to abnormalities such as zero voltage, lithium plating, and low capacity. Furthermore, the hydrolysis products are corrosive, further corroding the battery cell and module components, posing a significant safety hazard to users. This is especially true for pouch cells, which use relatively fragile aluminum-plastic film as the encapsulation material and are susceptible to damage due to encapsulation failure. Electrolyte leakage can have serious consequences, therefore, leakage detection of battery cells is essential.

[0025] Related technologies involve manual visual leakage detection of battery cells, relying on manual inspection of the surface for obvious damage points to determine if a leak has occurred. However, this method depends on the experience of the personnel, is time-consuming, has a high rate of missed detection, and cannot effectively identify through holes smaller than 0.8 mm.

[0026] Some technologies use helium detection to detect leaks. This involves injecting helium gas into the battery cell and then using a helium detector to determine if a leak has occurred. However, this method has a high false alarm rate and is not suitable for structures like pouch cells that cannot withstand internal pressure.

[0027] Some technologies use gas-sensitive detection to detect leaks. This involves using negative pressure to extract the electrolyte from the damaged cell, and then using a gas sensor to detect the electrolyte concentration to determine if a leak has occurred. While this method is suitable for detecting pouch cells, it often results in either missed or over-detection, making it difficult to determine a reasonable threshold to distinguish between leaking and non-leaking cells.

[0028] This phenomenon occurs because current gas-sensitive sensors typically employ N-type oxide semiconductors. N-type semiconductors are fabricated by doping with elements or creating oxygen vacancies to form defects. They possess extra electrons that do not participate in covalent bonds, making them easily excited into the conduction band. If an N-type semiconductor adsorbs reducing substances (such as volatile organic compounds (VOCs) from an electrolyte and gains electrons, the number of free electrons increases, conductivity increases, and resistance decreases. Conversely, if an N-type semiconductor adsorbs oxidizing substances (such as oxygen) and loses electrons, the number of free electrons decreases, conductivity weakens, and resistance increases. The sensor's detection mechanism is that the adsorption of reducing substances increases the number of electrons in the valence band, resulting in a significant change in conductivity. Combined with the sensor's testing circuit, this change in conductivity affects the voltage division of the testing resistor, thus outputting a signal as a voltage change.

[0029] Existing leakage detection systems typically place the gas-sensitive sensor and the battery cell under test in the same sealed chamber for detection. During the vacuuming process, due to the unstable vacuum level, oxygen vacancies are formed on the semiconductor surface, which increases the number of valence band electrons, thereby increasing conductivity and raising the output voltage, thus causing over-killing of normal battery cells.

[0030] In addition, the test temperature of gas-sensitive sensors is usually above 100℃. The airflow in the sealed chamber, which is close to room temperature, will cause the sensor temperature to drop sharply, which will affect the Fermi-Dirac distribution of its electrons, reduce the electron distribution in the conduction band, decrease conductivity, and cause the output voltage to drop, thus causing the problem of missing abnormal cells.

[0031] In addition, some leakage detection systems place the gas sensor in a sealed chamber for a long time. If the electrolyte in the battery cell leaks, the sealed chamber will be contaminated, and the VOCs adsorbed by the sensor cannot be effectively discharged, which will also lead to inaccurate detection results in the next test and cause over-killing.

[0032] Therefore, there is an urgent need for a battery cell leakage detection system with better detection performance.

[0033] The technical solution of this application will be described in detail below through specific embodiments.

[0034] In some embodiments of this application, a battery cell leakage detection system is provided, such as... Figure 1 As shown, it includes: a vacuum system 1; a first chamber 2 for placing the battery cell 2-7 to be tested; a first branch 3 connected between the vacuum system 1 and the first chamber 2, with a first valve group 3-1 connected to the first branch 3 for controlling the opening and closing of the first branch 3; a second branch 4 connected between the vacuum system 1 and the first chamber 2, with a second chamber 4-1 and a second valve group 4-2 connected to the second branch 4 for controlling the opening and closing of the second branch 4, and a leakage detector 4-3 installed inside the second chamber 4-1.

[0035] like Figure 1 The diagram shown is a schematic diagram of the module connection of a battery cell leakage detection system. The battery cell leakage detection system includes an air extraction system 1, a first chamber 2, a first branch 3, and a second branch 4.

[0036] The extraction system 1, for example, is a vacuum pump used for evacuation, providing the same vacuum environment as the gas-sensitive detection system for leaking battery cells. The first chamber 2 is used to house the battery cell 2-7 to be tested, providing a sealed detection environment for it. A first branch 3 and a second branch 4 are connected in parallel between the extraction system 1 and the first chamber 2. The first branch 3 directly connects the first chamber 2 and the extraction system 1, enabling the extraction system 1 to evacuate the first chamber 2 independently. The second branch 4 houses the leak detector 4-3, enabling the extraction system 1 to evacuate the environment surrounding the leak detector 4-3.

[0037] The first branch 3 is equipped with a first valve group 3-1, which may have one or more valves, for controlling the on / off state of the first branch 3. The second branch 4 is equipped with a second valve group 4-2, which may also have one or more valves, for controlling the on / off state of the second branch 4. The second branch 4 is also equipped with a second chamber 4-1 for housing a leak detector 4-3, which may be, for example, a VOC gas sensor, but is not specifically limited. By setting the first branch 3 and the second branch 4 in parallel between the vacuum system 1 and the first chamber 2, with the battery cell 2-7 housed in the first chamber 2, and the second branch 4 connected to the second chamber 4-1, where the leak detector 4-3 is housed, the battery cell 2-7 and the leak detector 4-3 can be relatively isolated, thus balancing the test pressure and providing a basis for improving the detection effect.

[0038] The vacuum system 1 of the battery cell leakage detection system can be in a normally open state. Before placing the battery cell 2-7, the first valve group 3-1 is opened and the second valve group 4-2 is closed. The vacuum system 1 can evacuate the second chamber 4-1 through the second branch 4. After the preset vacuum level is reached, the leakage detector 4-3 measures the first reading to provide a reference. Then, the first valve group 3-1 is closed and the first chamber 2 is opened. After placing the battery cell 2-7, the pressure in the first chamber 2 is at standard atmospheric pressure. At this time, the second valve group 4-2 is opened, and the vacuum system 1 can evacuate the first chamber 2 separately through the first branch 3 to ensure the stability of the vacuum level during subsequent testing. After the first chamber 2 is evacuated to the preset vacuum level, the first valve group 3-1 is opened and the second valve group 4-2 is closed. The leakage detector 4-3 can perform leakage detection on the battery cell 2-7 in an environment without cold air disturbance and with a stable vacuum level. The leakage detector 4-3 measures the second reading, and comparing the first and second readings confirms whether the battery cell 2-7 is leaking. This method can avoid strong interference from vacuuming on the signal of the leak detector 4-3, and tests have shown that it can avoid over-detection and under-detection problems.

[0039] This battery cell leakage detection system has a simple structure, is easy to manufacture, has strong stability, and good detection effect. It can effectively avoid the problems of over-detection and under-detection in the leakage detection of battery cells 2-7.

[0040] In some embodiments, such as Figure 2 As shown, the second valve group 4-2 includes a first connecting valve 4-21 and a second connecting valve 4-22. The first connecting valve 4-21 is connected between the second chamber 4-1 and the first chamber 2, and the second connecting valve 4-22 is connected between the second chamber 4-1 and the air extraction system 1.

[0041] like Figure 2 The diagram shows a schematic of a battery cell leakage detection system. The second valve group 4-2 includes a first connecting valve 4-21 and a second connecting valve 4-22. The connecting valves are, for example, solenoid valves. The first connecting valve 4-21 is located between the second chamber 4-1 and the first chamber 2, and the second connecting valve 4-22 is located between the second chamber 4-1 and the air extraction system 1. By setting two connecting valves to control the opening and closing of the second branch 4, the second chamber 4-1 can be isolated separately.

[0042] When the second connecting valve 4-22 is opened and the first connecting valve 4-21 and the first valve group 3-1 are closed, the second chamber 4-1 can be evacuated independently. When the first connecting valve 4-21 and the second connecting valve 4-22 are closed, the first reading can be measured using the leak detector 4-3 in a stable environment, resulting in more accurate detection. After closing the first connecting valve 4-21 and the second connecting valve 4-22, the second chamber 4-1 can also be repaired independently, making operation more convenient.

[0043] In some embodiments, such as Figure 2 As shown, a third chamber 3-2 is also connected to the first branch 3. The third chamber 3-2 is equipped with a filter element 3-3, which is used to filter the gas drawn into the first chamber 2 by the air extraction system 1.

[0044] like Figure 2 As shown, the first branch 3 is provided with a third chamber 3-2, and a filter element 3-3 is provided in the third chamber 3-2. The filter element 3-3 can filter the gas in the first chamber 2, so as to prevent the electrolyte vapor or other impurities of the battery cell 2-7 from damaging the pipe of the gas extraction system 1, causing damage and affecting the test results.

[0045] In some embodiments, such as Figure 2 As shown, the first valve group 3-1 includes a third connecting valve 3-11 and a fourth connecting valve 3-12. The third connecting valve 3-11 is connected between the third chamber 3-2 and the first chamber 2, and the fourth connecting valve 3-12 is connected between the third chamber 3-2 and the air extraction system 1.

[0046] like Figure 2As shown, the first valve group 3-1 includes a third connecting valve 3-11 and a fourth connecting valve 3-12. The connecting valves can be, for example, solenoid valves. The third connecting valve 3-11 is located between the third chamber 3-2 and the first chamber 2, while the fourth connecting valve 3-12 is located between the third chamber 3-2 and the extraction system 1. By controlling the opening and closing of the first branch 3 using these two connecting valves, the third chamber 3-2 can be isolated independently. After closing both the third connecting valve 3-11 and the fourth connecting valve 3-12, the third chamber 3-2 can be maintained independently, making operation more convenient.

[0047] In some embodiments, such as Figure 2 As shown, the second chamber 4-1 and the third chamber 3-2 are both columnar chambers. The leakage detector 4-3 is located in the center of the second chamber 4-1. The filter element 3-3 is an adsorption filter element 3-3.

[0048] like Figure 2 As shown, the second chamber 4-1 and the third chamber 3-2 can be cylindrical chambers, such as cylindrical pipes, which are readily available and occupy little space. The leak detector 4-3 is located at the center of the second chamber 4-1 and can be fixed by snap-fit ​​or bolt connection. The leak detector 4-3 has sufficient contact area with the electrolyte vapor, resulting in good detection performance. The filter element 3-3 can also be located at the center of the third chamber 3-2 and fixed by snap-fit. The filter element 3-3 is an adsorption filter element, for example, made of activated carbon, which can adsorb electrolyte vapor, resulting in better filtration.

[0049] In some embodiments, the vacuum system 1 includes two vacuum pumps, one of which is connected to the first branch 3 and the other is connected to the second branch 4.

[0050] The evacuation system 1 may include two vacuum pumps, each connected to a branch, so that one branch can be controlled to evacuate air separately, which facilitates the adjustment of different detection parameters.

[0051] In some embodiments, such as Figure 2 As shown, the first chamber 2 is connected to a pressure relief valve 2-1, which is used to control the connection and disconnection between the first chamber 2 and the external environment.

[0052] like Figure 2 As shown, the side wall of the first chamber 2 is provided with a pressure relief valve 2-1. The pressure relief valve 2-1 is, for example, a solenoid valve. Opening the pressure relief valve 2-1 can connect the interior of the first chamber 2 with the external environment and relieve the vacuum pressure. Closing the pressure relief valve 2-1 can ensure the sealed environment of the first chamber 2.

[0053] In some embodiments, such as Figure 2As shown, a camera 2-2 is provided in the first chamber 2, and the camera 2-2 is used to collect image information of the battery cell 2-7.

[0054] like Figure 2 As shown, a camera 2-2 is installed in the first chamber 2. The camera 2-2 is, for example, a CCD (charge-coupled device) camera, which has powerful scanning capabilities and good image clarity. The camera 2-2 is set up to acquire image information of the battery cell 2-7. By comparing battery cell photos taken in a vacuum environment and under normal pressure, the deformation of the aluminum-plastic film of the battery cell 2-7 can be detected.

[0055] In some embodiments, such as Figure 2 As shown, the first chamber 2 includes a cooperating cavity 2-3 and a cavity cover 2-4. The cavity cover 2-4 is driven by a drive device 2-5, which is used to control the opening and closing of the cavity cover 2-4. A moving platform 2-6 is provided inside the first chamber 2. The moving platform 2-6 is used to carry the battery cell 2-7 and drive the battery cell 2-7 to move.

[0056] like Figure 2 As shown, the first chamber 2 is, for example, a rectangular parallelepiped chamber, including a mating body 2-3 and a cover 2-4. The body 2-3 and the cover 2-4 are rotatably connected for easy opening and closing. A drive device 2-5 can be installed inside the first chamber 2. The drive device 2-5 is, for example, a hydraulic rod, which can be connected to the cover 2-4 to control the opening and closing of the cover 2-4 in order to retrieve the discharge core 2-7.

[0057] like Figure 2 As shown, the first chamber 2 is also equipped with a mobile platform 2-6, which is, for example, a mechanical lifting platform, which can carry the battery cell 2-7 and drive the battery cell 2-7 to rise and fall so as to remove and discharge the battery cell 2-7.

[0058] In some embodiments, such as Figure 3 As shown, the battery cell leakage detection system also includes a control unit 5, which is electrically connected to the drive device 2-5, the mobile platform 2-6, the air extraction system 1, the pressure relief valve 2-1, the first valve group 3-1, and the second valve group 4-2.

[0059] like Figure 3 The diagram shows a module connection schematic of a battery cell leakage detection system. The battery cell leakage detection system also includes a control unit 5, which is, for example, a PLC (Programmable Logic Controller). It is electrically connected to the drive device 2-5, the moving platform 2-6, the air extraction system 1, the pressure relief valve 2-1, the first valve group 3-1, and the second valve group 4-2. It can control the opening and closing of the cavity cover 2-4, control the movement of the battery cell 2-7, control the air extraction, and control the opening and closing of the valves.

[0060] In some embodiments, the operation method of the cell leakage detection system is specifically as follows: Figure 4 As shown, under normal conditions, pressure relief valve 2-1 is open, the first chamber 2 is connected to the external environment, the first connecting valve 4-21, the third connecting valve 3-11, and the fourth connecting valve 3-12 are closed, the second connecting valve 4-22 is open, and the evacuation system 1 evacuates the second chamber 4-1 to achieve a preset vacuum level (e.g., -85 kPa).

[0061] After placing the battery cell 2-7 into the first chamber 2, close the pressure relief valve 2-1 and take the first photo of the battery cell 2-7 through the camera 2-2.

[0062] Close the second connecting valve 4-22. At this time, the leakage detector 4-3 (VOC gas sensor) is in a stable vacuum pressure state. Under this state, read the sensor output voltage V1. Open the third connecting valve 3-11 and the fourth connecting valve 3-12. The evacuation system 1 evacuates the first chamber 2 and the third chamber 3-2 to reach the preset vacuum level (e.g., -85kPa). Take a second picture of the battery cell 2-7 through the camera 2-2.

[0063] By comparing two photos using image analysis algorithms, the number of pixels whose grayscale difference exceeds a preset difference value (e.g., 256 grayscale values) is determined. If the number of pixels exceeds the specified number (e.g., 10,000 pixels), it indicates that cell 2-7 is bulging, and a large hole leak has caused cell 2-7 to lose pressure balance. In this case, no further testing is needed to determine that cell 2-7 is leaking and has failed.

[0064] If the number of pixels does not exceed the specified number, close the third connecting valve 3-11 and the fourth connecting valve 3-12, and open the first connecting valve 4-21 and the second connecting valve 4-22 to connect the first chamber 2 and the second chamber 4-1. In this state, read the sensor output voltage V2. Since both chambers have been evacuated, the connection process will not cause strong cold air flow or changes in vacuum. The sensor can measure the concentration of volatile electrolyte vapor in a stable environment. If cell 2-7 leaks, due to the high electrolyte concentration in the first chamber 2, the concentration difference will drive the electrolyte vapor to diffuse into the second chamber 4-1, accurately measuring the actual electrolyte leakage without over- or under-detection.

[0065] After the test is completed, close the first connecting valve 4-21, open the pressure relief valve 2-1 to release pressure, restore to the initial state, move the battery cell 2-7 out using the moving platform 2-6, calculate the difference between V2 and V1, if the difference is greater than the threshold (e.g., 0.1V), it is determined that the battery cell 2-7 has microporous electrolyte leakage.

[0066] In some embodiments, the cell leakage detection system was used to perform leakage tests on different normal cells without leakage, and different gas sensors were used for comparison. The operation method was the same as in the above embodiment, with a pumping time of 2 seconds and a reading time of 3 seconds. The test results are shown in Table 1.

[0067] Table 1 Normal Cell Test Table

[0068]

[0069] In contrast, the same battery cell was tested using a traditional leakage detection system. The traditional leakage detection system has only one chamber connected to the vacuum system, and the gas sensor is fixed in the chamber. When the chamber is not evacuated and the battery cell is not discharged, the sensor output voltage V1 is read. Then the battery cell is placed in the chamber and evacuated, and the sensor output voltage V2 is read. Different gas sensors were used for comparison. The vacuuming time was 5 seconds and the reading time was 3 seconds. The test results are shown in Table 2.

[0070] Table 2 Normal Cell Test Table

[0071]

[0072] As shown in Table 1, the test results for normal battery cells in this embodiment are stable within [-0.024, 0.000]. Stable test results can be maintained even when using different gas sensors and different battery cells, without overkill. In contrast, as shown in Table 2, the test results for normal battery cells using the traditional method are not stable, with fluctuations reaching [-0.098, 0.229]. Some results exceed the product specification threshold (V2-V1 > 0.1V), indicating significant overkill.

[0073] In some embodiments, the battery cell leakage detection system was used to perform leakage tests on different abnormal battery cells with leakage, and different gas sensors were used for comparison. In this case, the abnormal battery cell was punctured with a needle at different locations to create micropores with a diameter of about 0.5 mm in the aluminum-plastic film, and the electrolyte was squeezed out. The evacuation time was 2 seconds and the reading time was 3 seconds. The test results are shown in Table 3.

[0074] Table 3 Abnormal Cell Test Table

[0075]

[0076] In comparison, the same battery cell was tested using a traditional leakage detection system, and different gas sensors were used for comparison. The evacuation time was 5 seconds and the reading time was 3 seconds. The test results are shown in Table 4.

[0077] Table 4 Abnormal Cell Test Table

[0078]

[0079] As shown in Table 3, this embodiment can detect 100% of abnormal battery cells. Since the electrolyte in the battery cell crystallizes in the pores after evaporation, the amount of electrolyte evaporation gradually decreases with the number of tests. This trend can be observed in the results of different test runs for the same battery cell in this verification, which is consistent with the expected trend, indicating reliable results. In contrast, as shown in Table 4, the test results of abnormal battery cells using the traditional method are very unstable. Half of the sensors showed negative voltage differences for leaking samples, failing to detect leaking battery cells and exhibiting a clear phenomenon of missed detection.

[0080] In summary, this embodiment can detect leaking battery cells more stably, quickly and effectively than traditional solutions, and can effectively prevent over-kill and under-kill problems.

[0081] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0082] Furthermore, given that details have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that embodiments of this application may be practiced without these details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0083] Although this application has been described in conjunction with embodiments thereof, many substitutions, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description.

[0084] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A battery cell leakage detection system, characterized in that, include: Air extraction system; The first chamber is used to place the battery cell to be tested; The first branch is connected between the air extraction system and the first chamber. A first valve group is connected to the first branch, and the first valve group is used to control the opening and closing of the first branch. The second branch is connected between the air extraction system and the first chamber. The second branch is connected to a second chamber and a second valve group. The second valve group is used to control the on / off state of the second branch. A leak detector is installed inside the second chamber.

2. The cell leakage detection system according to claim 1, characterized in that, The second valve assembly includes a first connecting valve and a second connecting valve, wherein the first connecting valve is connected between the second chamber and the first chamber, and the second connecting valve is connected between the second chamber and the air extraction system.

3. The cell leakage detection system according to claim 1, characterized in that, The first branch is also connected to a third chamber, which is equipped with a filter element for filtering the gas drawn from the first chamber by the air extraction system.

4. The cell leakage detection system according to claim 3, characterized in that, The first valve assembly includes a third connecting valve and a fourth connecting valve. The third connecting valve is connected between the third chamber and the first chamber, and the fourth connecting valve is connected between the third chamber and the air extraction system.

5. The cell leakage detection system according to claim 3, characterized in that, Both the second chamber and the third chamber are cylindrical chambers. The leakage detector is located in the center of the second chamber. The filter element is an adsorption filter element.

6. The cell leakage detection system according to claim 1, characterized in that, The pumping system includes two vacuum pumps, one of which is connected to the first branch and the other is connected to the second branch.

7. The cell leakage detection system according to claim 1, characterized in that, The first chamber is connected to a pressure relief valve, which is used to control the connection between the first chamber and the external environment.

8. The cell leakage detection system according to claim 1, characterized in that, A camera is installed in the first chamber, and the camera is used to collect image information of the battery cell.

9. The cell leakage detection system according to claim 7, characterized in that, The first chamber includes a mating cavity and a cavity cover. The cavity cover is driven by a drive device, which is used to control the opening and closing of the cavity cover. A moving platform is provided in the first chamber, which is used to carry the battery cell and drive the battery cell to move.

10. The cell leakage detection system according to claim 9, characterized in that, It also includes a control unit, which is electrically connected to the drive device, the mobile platform, the air extraction system, the pressure relief valve, the first valve group, and the second valve group, respectively.

Images