Liquid leakage detection method and liquid leakage detection device for battery module

Abstract

The invention provides a liquid leakage detection method and a liquid leakage detection device for a battery module, and relates to the technical field of batteries. According to the liquid leakage detection method of the battery module provided by the invention, the expansion direction of the battery cell is limited by using external pressing force, meanwhile, the negative pressure in the battery cell is simulated through a vacuum environment, a controllable condition for deformation of the battery cell is formed, the change of the distance between positive and negative tabs caused by expansion of the battery cell is amplified, and the detection sensitivity is improved; by detecting the change rate of the pressing force along with the change of the environmental pressure, the rapid and high-precision detection of the battery module is realized, the problem of low detection efficiency of a traditional single cell is solved, the improvement of the battery production efficiency and the product reliability is facilitated, and the method is suitable for a large-scale production scene. The liquid leakage detection device of the battery module provided by the invention is simple in structure, and liquid leakage detection of the battery module can be quickly and accurately realized.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular, to a method and a device for detecting liquid leakage of a battery module. Background Art

[0002] The existing liquid leakage detection of soft-pack battery modules has the following problems:

[0003] 1. Traditional liquid leakage detection of soft-pack batteries mostly uses visual inspection, electrolyte composition analysis or destructive testing, which is inefficient and costly.

[0004] 2. Some methods detect the surface deformation or internal pressure change of the battery, but it is difficult to achieve accurate judgment at the module level (multiple battery cells combined), and it is easily affected by the environment.

[0005] 3. The correlation between the internal negative pressure characteristics of the battery and the external pressure change is not combined, resulting in insufficient detection sensitivity.

[0006] Therefore, for the liquid leakage problem of module-level soft-pack batteries, a non-destructive, fast and high-precision detection method is needed to improve production efficiency and product reliability.

[0007] In view of this, the present invention is specifically proposed. Summary of the Invention

[0008] The first object of the present invention is to provide a method for detecting liquid leakage of a battery module to solve the above technical problems.

[0009] The second object of the present invention is to provide a device for detecting liquid leakage of a battery module.

[0010] To achieve the above objects, the following technical solutions are specifically adopted:

[0011] In a first aspect, the present invention provides a method for detecting liquid leakage of a battery module, including the following steps:

[0012] a. Apply a pressing force to the battery along the arrangement direction of the battery cells in the battery module and fix it, then reduce the pressure of the environment where the soft-pack battery module is located, and at the same time detect the pressing force, and calculate the change rate k of the pressing force with respect to the change in the environmental pressure;

[0013] b. Detect the change in the distance between the positive and negative electrode tabs of the battery cell before and after the change in the environmental pressure;

[0014] If k = N×W×L and the distances between the positive and negative electrode tabs of the battery cell all change, then the battery module does not leak liquid;

[0015] If k < N×W×L and the distance between the positive and negative electrode tabs of one or more battery cells does not change, then the battery module leaks liquid;

[0016] Wherein, N is the number of battery cells in the battery module, W is the width of the battery module on the surface where the pressing force is applied, and L is the length of the battery module on the surface where the pressing force is applied.

[0017] As a further technical solution, the magnitude of the pressing force is 40 - 80 kgf.

[0018] As a further technical solution, reducing the pressure in the environment where the soft-pack battery module is located is to reduce the pressure by 20 kPa to 40 kPa.

[0019] As a further technical solution, detect the data of the pressing force under different ambient pressure changes, and calculate the change rate of the pressing force with the ambient pressure by linear fitting.

[0020] As a further technical solution, if there is liquid leakage in the battery module, the number of leaking battery cells is determined according to the following formula:

[0021] n = N - k / (W×L);

[0022] Wherein, n is the number of leaking battery cells.

[0023] As a further technical solution, if there is liquid leakage in the battery module, determine the leaking battery cells according to whether the distance between the positive and negative electrode tabs changes before and after the ambient pressure change.

[0024] In a second aspect, the present invention provides a liquid leakage detection device for a battery module, including a pressing tooling, a sealing box, a vacuum pump, a camera and a control system;

[0025] The pressing tooling is arranged inside the sealing box and includes a battery slot and clamps arranged on both sides of the battery slot; the battery slot is used for placing the battery module, and the clamps are used for applying a pressing force to the battery module;

[0026] One side of the clamp is provided with a pressure sensor for detecting the pressing force;

[0027] The vacuum pump is connected to the sealing box and is used for providing negative pressure to the sealing box;

[0028] The camera is arranged above the battery slot inside the sealing box and is used for detecting the distance between the positive and negative electrode tabs of the battery;

[0029] The control system is used for controlling the operation of the clamps and the vacuum pump, and the acquisition and analysis of the data of the camera and the pressure sensor.

[0030] As a further technical solution, the sealing box includes a bottom plate and a sealing cover, and the bottom plate and the sealing cover are sealed after being closed.

[0031] As a further technical solution, a negative pressure sensor is arranged on the vacuum pump for detecting the pressure inside the sealing cover.

[0032] As a further technical solution, it further includes a camera, and the camera includes a CCD camera.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The method for detecting liquid leakage of the battery module provided by the present invention utilizes an external pressing force to restrict the expansion direction of the battery cell. At the same time, it simulates the negative pressure inside the battery cell through a vacuum environment to form controllable conditions for the deformation of the battery cell, amplifies the change in the distance between the positive and negative electrode tabs caused by the expansion of the battery cell, and improves the detection sensitivity; by detecting the change rate of the pressing force with the change of the environmental pressure, it realizes rapid and high-precision detection of the battery module, solves the problem of low detection efficiency of traditional single battery cell detection, helps to improve the battery production efficiency and product reliability, and adapts to large-scale production scenarios. Description of the Drawings

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a device for detecting liquid leakage of a battery module provided in Embodiment 1 of the present invention;

[0037] Figure 2 It is the difference in the rising slopes of the pressures of non-liquid-leaking batteries and liquid-leaking batteries with the increase of vacuum degree;

[0038] Figure 3 It is the pressing force of different liquid-leaking batteries.

[0039] Reference numerals: 1 - pressing tooling; 11 - battery slot; 12 - fixture; 13 - pressure sensor; 2 - sealing box; 21 - bottom plate; 22 - sealing cover; 3 - vacuum pump; 4 - camera. Detailed Embodiments

[0040] The following will describe the implementation schemes of the present invention in detail in combination with the embodiments and examples. However, those skilled in the art will understand that the following embodiments and examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. Those not specifying specific conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specifying the manufacturer can be obtained as conventional products through commercial purchase.

[0041] In a first aspect, the present invention provides a method for detecting liquid leakage of a battery module, comprising the following steps:

[0042] a. Apply a pressing force to the battery along the arrangement direction of battery cells in the battery module and fix it. Then, reduce the pressure of the environment where the soft-pack battery module is located, and at the same time, detect the pressing force and calculate the change rate k of the pressing force with respect to the change in the environmental pressure;

[0043] b. Detect the change in the distance between the positive and negative electrode tabs of the battery cell before and after the change in the environmental pressure;

[0044] If k = N×W×L and the distances between the positive and negative electrode tabs of the battery cell both change, then the battery module does not leak liquid;

[0045] If k < N×W×L and the distance between the positive and negative electrode tabs of a battery cell does not change, then the battery module leaks liquid;

[0046] Wherein, N is the number of battery cells in the battery module, W is the width of the battery module on the surface where the pressing force is applied, and L is the length of the battery module on the surface where the pressing force is applied.

[0047] In the present invention, the calculation formula for the change in the pressing force is as follows:

[0048] ΔF = N×(W×L×ΔP);

[0049] Wherein, ΔF is the change in the pressing force, and ΔP is the change in the environmental pressure.

[0050] Therefore, the theoretical change rate k is k = ΔF / ΔP = N×W×L.

[0051] In some optional embodiments, the magnitude of the pressing force can be, for example, but not limited to, 40 kgf, 60 kgf, or 80 kgf.

[0052] It has been found by the inventor that if the pressing force is too small, the battery will not be fixed tightly, which is likely to cause the battery to loosen or it is difficult to observe the battery expansion. It is more appropriate to use a pressing force of 40 kgf - 80 kgf.

[0053] In some optional embodiments, reducing the pressure of the environment where the soft-pack battery module is located means reducing the pressure by 20 kPa to 40 kPa, which can be, for example, 20 kPa, 30 kPa, or 40 kPa.

[0054] It has been found by the inventor that if the pressure reduction is too small, the k value detection will be inaccurate; if the pressure reduction is too large, it will cause damage to the battery.

[0055] By further optimizing and adjusting the pressing force and the amount of pressure reduction of the environment, the stability and sensitivity of the detection are ensured.

[0056] In some alternative embodiments, data of the pressing force under different ambient pressure changes is detected, and the change rate of the pressing force with respect to the ambient pressure is calculated by linear fitting.

[0057] Linear fitting helps to obtain a more accurate k value.

[0058] In some alternative embodiments, if there is liquid leakage in the battery module, the number of leaking battery cells is determined according to the following formula:

[0059] n = N - k / (W × L);

[0060] Where n is the number of leaking battery cells.

[0061] The leaking battery cells cannot expand due to the loss of sealing, and the pressure value tends to be stable or decrease; the normal battery cells cause the pressing force to continuously increase due to expansion. Therefore, the number of leaking battery cells can be calculated through the k value.

[0062] In some alternative embodiments, if there is liquid leakage in the battery module, the leaking battery cells are determined according to whether the distance between the positive and negative electrode tabs changes before and after the ambient pressure changes.

[0063] In a second aspect, the present invention provides a liquid leakage detection device for a battery module, including a pressing tooling 1, a sealing box 2, a vacuum pump 3, a camera 4, and a control system;

[0064] The pressing tooling 1 is disposed inside the sealing box 2 and includes a battery slot 11 and clamps 12 disposed on both sides of the battery slot 11; the battery slot 11 is used for placing the battery module, and the clamps 12 are used for applying a pressing force to the battery module;

[0065] A pressure sensor 13 is disposed on one side of the clamp 12 for detecting the pressing force;

[0066] The vacuum pump 3 is connected to the sealing box 2 for providing a negative pressure to the sealing box 2;

[0067] The camera 4 is disposed above the battery slot 11 inside the sealing box 2 for detecting the distance between the positive and negative electrode tabs of the battery;

[0068] The control system is used for controlling the operations of the clamp 12 and the vacuum pump 3, and for collecting and analyzing the data of the camera 4 and the pressure sensor 13.

[0069] This device has a simple structure and can quickly and accurately detect the liquid leakage of the battery module.

[0070] In some alternative embodiments, the pressure sensor 13 includes an HBM U10M pressure sensor.

[0071] In some alternative embodiments, the sealed box 2 includes a bottom plate 21 and a sealing cover 22, and the bottom plate 21 and the sealing cover 22 are closed to achieve sealing.

[0072] In some alternative embodiments, a negative pressure sensor is provided on the vacuum pump 3 for detecting the pressure inside the sealing cover.

[0073] In some alternative embodiments, a camera 4 is further included, and the camera 4 includes a CCD camera.

[0074] In some alternative embodiments, the control system is a PLC integrated module.

[0075] The present invention will be further described below through specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way.

[0076] Embodiment 1

[0077] A liquid leakage detection device for a battery module, as Figure 1 shown, includes a pressing tooling 1, a sealed box 2, a vacuum pump 3, a camera 4, and a control system;

[0078] The pressing tooling 1 is disposed inside the sealed box 2 and includes a battery slot 11 and clamps 12 disposed on both sides of the battery slot 11; the battery slot 11 is used for placing the battery module, and the clamps 12 are used for applying a pressing force to the battery module;

[0079] A pressure sensor 13 is disposed on one side of the clamp 12 for detecting the pressing force;

[0080] The sealed box 2 includes a bottom plate 21 and a sealing cover 22, and the bottom plate 21 and the sealing cover 22 are closed to achieve sealing;

[0081] The vacuum pump 3 is connected to the sealed box 2 for providing negative pressure to the sealed box 2; a negative pressure sensor is provided on the vacuum pump 3 for detecting the pressure inside the sealing cover;

[0082] The camera 4 is disposed above the battery slot 11 inside the sealed box 2 for detecting the distance between the positive and negative electrode tabs of the battery;

[0083] The control system is a PLC integrated module for controlling the operations of the clamps 12 and the vacuum pump 3, as well as collecting and analyzing the data of the camera 4 and the pressure sensor 13.

[0084] Embodiment 2

[0085] Using the device of Embodiment 1 to detect liquid leakage of a battery module includes the following steps:

[0086] 1. Place the battery module to be tested in the battery slot 11. The control system controls the fixture 12 to apply a pressing force of 50 kgf to the battery module and complete the fixation;

[0087] 2. Cover the sealing cover 22 so that the bottom plate 21 and the sealing cover 22 are closed and sealed;

[0088] 3. The control system controls the vacuum pump 3 to start, reducing the pressure in the sealed box 2. At the same time, every time the pressure drops by 10 kPa, collect the data of the pressure sensor 13 until the pressure drops by 40 kPa;

[0089] 4. Before and after the vacuum pump 3 evacuates the air, the camera 4 takes pictures, and the control system analyzes the change in the distance between the positive and negative electrode tabs of the battery cells;

[0090] If k = N × W × L and the distances between the positive and negative electrode tabs of all the battery cells change, then the battery module does not leak liquid;

[0091] If k < N × W × L and the distance between the positive and negative electrode tabs of one or more battery cells does not change, then the battery module leaks liquid;

[0092] Where N is the number of battery cells in the battery module, W is the width of the battery module on the surface where the pressing force is applied, L is the length of the battery module on the surface where the pressing force is applied, and k is the rate of change of the pressing force with respect to the ambient pressure change.

[0093] Test Example 1

[0094] Use the method of Example 2 to detect a module of 32 pcs non-leaking battery cells (length 0.15 m, width 0.1 m). Evacuate the air and reduce the pressure in the sealed box 2 by 40 kPa within 30 s. It is measured that the pressing force rises from the initial 50 kgf to 1970 kgf. Plot the pressure change in the sealed box 2 and the pressing force change, as shown in Figure 2 ( Figure 2 In the figure, the abscissa is the degree of vacuum, so k is the absolute value of the slope of this figure), and it is measured that k is 48 kgf / kPa. And deformation is detected in the camera image, which is judged to be qualified. There is no leaking battery cell in the module, which is consistent with the actual situation.

[0095] Use the method of Example 2 to detect a module of 32 pcs leaking battery cells (3 battery cells are leaking, length 0.15 m, width 0.1 m). Evacuate the air and reduce the pressure in the sealed box 2 by 40 kPa within 30 s. It is measured that the pressing force rises from the initial 50 kgf to 1740 kgf. Plot the pressure change in the sealed box 2 and the pressing force change, as shown in Figure 2 As shown, it is measured that k is 43.5 kgf / kPa. And no deformation is detected in the camera image (a total of 3 are detected, and it is verified that these three battery cells are leaking), which is judged to be unqualified. There is no leaking battery cell in the module, which is consistent with the actual situation.

[0096] The module stack of 32 battery cells (length 0.15 m, width 0.1 m) is successively mixed with 0 pc, 1 pc, 3 pc, 5 pc, and 9 pc of leaking battery cells, and the method of Example 2 is respectively used for detection. The pressing forces when the pressure in the sealed box 2 drops by 40 kPa are respectively counted. The results are as Figure 3 shown. It can be seen from the results that the leaking battery modules can be screened out 100% according to the 1900 kgf screening standard.

[0097] It should be noted that 1 kgf refers to the gravity received by an object of 1 kg, that is, 1 kgf = 1 kg × g, where g is the acceleration due to gravity. In this test example, the pressing force is measured by an instrument, and after measurement, the instrument converts it into kilogram-force according to the above formula, and in the measuring instrument, g is set to 10 N / kg.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; 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 invention.

Claims

1. A method for detecting liquid leakage of a battery module, characterized in that, It includes the following steps: a. Apply a pressing force to the battery along the arrangement direction of battery cells in the battery module and fix it. Then, reduce the pressure of the environment where the soft-pack battery module is located, and at the same time detect the pressing force and calculate the change rate k of the pressing force with the change of the environmental pressure; b. Detect the change in the distance between the positive and negative electrode tabs of the battery cells before and after the change in the environmental pressure; If k = N × W × L and the distances between the positive and negative electrode tabs of the battery cells all change, then the battery module does not leak liquid; If k < N × W × L and the distance between the positive and negative electrode tabs of some battery cells does not change, then the battery module leaks liquid; Wherein, N is the number of battery cells in the battery module, W is the width of the battery module on the surface where the pressing force is applied, and L is the length of the battery module on the surface where the pressing force is applied.

2. The method for detecting liquid leakage of the battery module according to claim 1, wherein The magnitude of the pressing force is 40 - 80 kgf.

3. The method for detecting liquid leakage of the battery module according to claim 1, wherein Reducing the pressure of the environment where the soft-pack battery module is located means reducing the pressure by 20 kPa to 40 kPa.

4. The method for detecting liquid leakage of the battery module according to claim 1, wherein, Detect the data of the pressing force under different changes in the environmental pressure, and calculate the change rate of the pressing force with the environmental pressure by linear fitting.

5. The method for detecting liquid leakage of the battery module according to claim 1, wherein, If the battery module leaks liquid, then determine the number of leaking battery cells according to the following formula: n = N - k / (W × L); Wherein, n is the number of leaking battery cells.

6. The liquid leakage detection method of the battery module according to claim 1, wherein If the battery module leaks liquid, then determine the leaking battery cells according to whether the distance between the positive and negative electrode tabs changes before and after the change in the environmental pressure.

7. A leakage detection device for a battery module, characterized in that, It includes a pressing tool (1), a sealing box (2), a vacuum pump (3), a camera (4) and a control system; The pressing tool (1) is arranged in the sealing box (2) and includes a battery slot (11) and clamps (12) arranged on both sides of the battery slot (11); the battery slot (11) is used to place the battery module, and the clamps (12) are used to apply a pressing force to the battery module; One side of the clamp (12) is provided with a pressure sensor (13) for detecting the pressing force; The vacuum pump (3) is connected to the sealing box (2) and is used to provide negative pressure to the sealing box (2); The camera (4) is arranged above the battery slot (11) in the sealing box (2) and is used to detect the distance between the positive and negative electrode tabs of the battery; The control system is used to control the operation of the clamp (12) and the vacuum pump (3), and the acquisition and analysis of the data of the camera (4) and the pressure sensor (13).

8. The liquid leakage detection device for the battery module according to claim 7, characterized in that The sealing box (2) includes a bottom plate (21) and a sealing cover (22), and the bottom plate (21) and the sealing cover (22) are sealed after being closed.

9. The liquid leakage detection device for the battery module according to claim 7, wherein, The vacuum pump (3) is provided with a negative pressure sensor for detecting the pressure inside the sealing cover.

10. The liquid leakage detection device for the battery module according to claim 7, characterized in that, It also includes that the camera (4) includes a CCD camera.

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