Breathable membrane type lithium ion battery electrolyte leakage mark

Abstract

The invention discloses a breathable film type lithium ion battery electrolyte standard leakage device, and relates to the field of lithium ion batteries. The leakage mark comprises a leakage mark body and a breathable film, and a liquid storage cavity is formed in the leakage mark body; a vent hole is formed in the leakage mark body, and the liquid storage cavity is communicated with the outside of the leakage mark body through the vent hole; the breathable film is mounted in the breathable opening; the gas-permeable membrane is of a layered structure and comprises a high-strength supporting layer and an organic gas diffusion layer; the organic gas diffusion layer permeates into the high-strength supporting layer to form a permeation composite layer, and the thickness of the permeation composite layer accounts for 0%-100% of the thickness of the high-strength supporting layer. The device is simple and reliable in structure, electrolyte can be adopted as a calibration object, the current stabilization effect is achieved through the breathable film, electrolyte gas can overflow at a stable rate, and the accuracy and reliability of calibration, calibration and spot inspection of existing liquid leakage detection equipment are improved.

Description

Technical Field

[0001] The invention relates to the field of lithium ion batteries, and in particular to a gas permeable membrane type lithium ion battery electrolyte leakage marker. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, high voltage, environmental protection, long life and fast charging. They are widely used in portable devices, electric vehicles, energy storage systems and other fields. In the application process, the safety of lithium-ion batteries is of great significance. Whether the lithium-ion electrolyte leaks is one of the main safety assessment criteria for lithium-ion batteries. At present, mass spectrometer leak detectors / equipment are usually used to detect lithium-ion battery electrolyte leaks, but existing mass spectrometer leak detectors / equipment currently do not have leak standards that can be used for calibration, calibration and spot inspection.

[0003] At present, lithium-ion battery volatile organic compound (VOC) leak detectors / equipment are calibrated, marked or inspected by using isobutylene gas of known concentration instead of directly using the electrolyte of the object to be measured. However, due to the different ionization efficiencies of different substances, the results of calibration, marking or inspection using isobutylene gas are not accurate. Therefore, it is necessary to develop a leak calibration that uses electrolyte as a calibration object to improve the accuracy of calibration / marking of VOC leak detectors / equipment. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned prior art, a breathable membrane type lithium-ion battery electrolyte leakage calibration is provided, in which the electrolyte is used as a calibration object, and the electrolyte gas is allowed to overflow at a stable rate through a breathable membrane component, thereby improving the accuracy and reliability of calibration, demarcation and inspection.

[0005] The present invention provides the following technical solutions:

[0006] The invention provides a breathable membrane type lithium ion battery electrolyte leak, comprising a leak body and a breathable membrane, wherein the leak body is provided with a liquid storage cavity; the leak body is provided with a breathable port, and the liquid storage cavity is communicated with the outside of the leak body through the breathable port; the breathable membrane is installed in the breathable port; the breathable membrane is a layered structure, and the breathable membrane comprises a high-strength support layer and an organic gas diffusion layer; the organic gas diffusion layer penetrates into the high-strength support layer to form a permeable composite layer, and the thickness of the permeable composite layer accounts for 0%-100% of the thickness of the high-strength support layer.

[0007] Preferably, the organic gas diffusion layer is provided with two layers, and the high-strength support layer is located between the two layers of organic gas diffusion layers.

[0008] Preferably, the breathable membrane further comprises an adhesive layer, and the adhesive layer is connected to the high-strength support layer; the high-strength support layer is located between the adhesive layer and the organic gas diffusion layer.

[0009] Preferably, the adhesive layer is provided with two layers, and the high-strength support layer and the organic gas diffusion layer are located between the two adhesive layers.

[0010] Furthermore, the material of the organic gas diffusion layer is selected from one of perfluorosulfonic acid resin, polymethylpentene, polyimide and graphene oxide.

[0011] Furthermore, the material of the high-strength support layer is selected from one of polyamide, polyolefin and polytetrafluoroethylene.

[0012] Furthermore, the material of the adhesive layer is selected from one of epoxy resin, silicone, fluorinated rubber and acrylic glue.

[0013] Furthermore, the thickness of the organic gas diffusion layer is 0.01 mm-5 mm.

[0014] Furthermore, the high-strength support layer is 0.1mm-5mm.

[0015] Furthermore, the thickness of the adhesive layer is 0.1 mm-3 mm.

[0016] Furthermore, it also includes a support plate, which is arranged at the upper and lower ends of the breathable membrane, and has through holes.

[0017] Furthermore, it also includes a connecting and fixing mechanism, which is installed in the air vent; the air permeable membrane and the support plate are installed on the connecting and fixing mechanism and are installed in the air vent through the connecting and fixing mechanism.

[0018] Preferably, the adhesive layer can bond the breathable membrane to the support plate.

[0019] Furthermore, it also includes a mark leak upper cover, which is arranged above the breathable membrane and is used to seal the mark leak.

[0020] Preferably, a sealing ring is provided between the support plate and the connecting and fixing mechanism.

[0021] The present invention has the following beneficial technical effects:

[0022] The breathable membrane type lithium ion battery electrolyte leakage calibration structure of the present invention is simple, and the electrolyte can be used to calibrate, demarcate and inspect the lithium ion battery leakage detection device; the structural design of the breathable membrane can make the electrolyte gas volatilize stably, further ensuring the accuracy and reliability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of a standard leakage and explosion of electrolyte in a breathable membrane type lithium ion battery provided by the present invention.

[0025] Figure 2 This is a structural diagram of the breathable membrane provided in Example 1 of the present invention.

[0026] Figure 3 This is a diagram of the breathable membrane structure provided in Example 2 of the present invention.

[0027] Figure 4 This is a diagram of the breathable membrane structure provided in Example 3 of the present invention.

[0028] Figure 5 This is a diagram of the breathable membrane structure provided in Example 4 of the present invention.

[0029] Figure 6 This is a diagram of the breathable membrane structure provided in Example 6 of the present invention.

[0030] Figure 7 This is a graph showing the stability test results of Example 1 and Comparative Examples 1-4 provided by the present invention.

[0031] Figure 8 This is a graph showing the stability test results of Example 1, Comparative Example 5 and Comparative Example 6 provided by the present invention.

[0032] Fig. 9 This is a graph showing the long-term stability test results of Example 1 provided by the present invention.

[0033] Description of the symbols in the figure:

[0034] 1-marking leak body; 2-liquid storage chamber; 3-air vent; 4-connecting and fixing mechanism; 5-support plate; 6-breathable membrane; 601-organic gas diffusion layer; 602-high-strength support layer; 603-permeable composite layer; 604-adhesive layer; 604A-first adhesive layer; 604B-second adhesive layer; 7-marking leak upper cover; 8-sealing ring. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0037] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0038] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] It should be noted that when testing samples prepared by the same scheme, there will be certain fluctuations in the results, which does not mean that the data are wrong.

[0040] Example 1

[0041] See also Figure 1The breathable membrane type lithium ion battery electrolyte leak shown includes a leak body 1, a breathable membrane 6, a support plate 5, a connecting and fixing mechanism 4 and a leak cover 7. A liquid storage chamber 2 is provided in the leak body 1; a vent 3 is provided on the leak body 1, and the liquid storage chamber 2 is connected to the outside of the leak body 1 through the vent 3; the breathable membrane 6 is installed in the vent 3. The support plate 5 is provided with two pieces, which are respectively arranged at the upper and lower ends of the breathable membrane 6, and a through hole for gas circulation is opened on the support plate 5. The connecting and fixing mechanism 4 is installed in the vent 3; the breathable membrane 6 and the support plate 5 are installed in the connecting and fixing mechanism 4, and are arranged in the vent 3 through the connecting and fixing mechanism 4. A sealing ring 8 is provided between the support plate 5 and the connecting and fixing mechanism 4, and the sealing performance of the connection is ensured by pressing the sealing ring 8. The leak cover 7 is provided on the top of the breathable membrane 6 to seal the leak.

[0042] For more details, please refer to Figure 2 The breathable membrane 6 is a three-layer structure, including a high-strength support layer 602, an organic gas diffusion layer 601 and an adhesive layer 604, wherein the adhesive layer 604 is connected to the high-strength support layer 602; the high-strength support layer 602 is located between the adhesive layer 604 and the organic gas diffusion layer 601; the organic gas diffusion layer 601 penetrates into the high-strength support layer 602 to form a permeable composite layer 603.

[0043] Specifically, the organic gas diffusion layer 601 is made of graphene oxide; the high-strength support layer 602 is made of polyamide; and the adhesive layer 604 is made of silica gel.

[0044] Specifically, the thickness of the organic gas diffusion layer 601 is 0.57 mm, the thickness of the high-strength support layer 602 is 2.33 mm, the thickness of the adhesive layer 604 is 0.86 mm, and the thickness of the permeable composite layer 603 accounts for 50% of the thickness of the high-strength support layer 602 .

[0045] Example 2

[0046] The difference between this embodiment and embodiment 1 lies in the difference in the air permeable membrane 6 .

[0047] Please refer to Figure 3 In this embodiment, the breathable membrane 6 is a double-layer structure, including a high-strength support layer 602 and an organic gas diffusion layer 601 , and the organic gas diffusion layer 601 penetrates into the high-strength support layer 602 to form a permeable composite layer 603 .

[0048] Specifically, the organic gas diffusion layer 601 is made of perfluorosulfonic acid resin; and the high-strength support layer 602 is made of polyolefin.

[0049] Specifically, the thickness of the organic gas diffusion layer 601 is 5 mm; the thickness of the high-strength support layer 602 is 5 mm; the thickness of the permeable composite layer 603 accounts for 0% of the thickness of the high-strength support layer 602 , that is, in this embodiment, the organic gas diffusion layer 601 does not penetrate into the high-strength support layer 602 .

[0050] Example 3

[0051] The difference between this embodiment and embodiment 1 lies in the difference in the air permeable membrane 6 .

[0052] Please refer to Figure 4 In this embodiment, the breathable membrane 6 is a three-layer structure, including a high-strength support layer 602 and two organic gas diffusion layers 601. The high-strength support layer 602 is arranged between the two organic gas diffusion layers 601, and the two organic gas diffusion layers 601 both penetrate into the high-strength support layer 602 to form a permeable composite layer 603.

[0053] Specifically, the two organic gas diffusion layers 601 are both made of polyimide; and the high-strength support layer 602 is made of polytetrafluoroethylene.

[0054] Specifically, the thicknesses of the two organic gas diffusion layers 601 are 0.01 mm and 0.05 mm respectively, and the thickness of the high-strength support layer 602 is 0.1 mm; the thickness of the permeable composite layer 603 accounts for 33% of the thickness of the high-strength support layer 602, wherein the penetration depth of the organic gas diffusion layer 601 with a thickness of 0.01 mm into the high-strength support layer 602 is 8% of the high-strength support layer 602, and the penetration depth of the organic gas diffusion layer 601 with a thickness of 0.05 mm into the high-strength support layer 602 is 25% of the high-strength support layer 602.

[0055] Example 4

[0056] The difference between this embodiment and embodiment 1 lies in the difference in the air permeable membrane 6 .

[0057] Please refer to Figure 5 In this embodiment, the breathable membrane 6 is a four-layer structure, including a high-strength support layer 602, an organic gas diffusion layer 601 and two adhesive layers 604, the adhesive layer 604 includes a first adhesive layer 604A and a second adhesive layer 604B, the first adhesive layer 604A is connected to the organic gas diffusion layer 601, the second adhesive layer 604B is connected to the high-strength support layer 602, the high-strength support layer 602 and the organic gas diffusion layer 601 are arranged between the two adhesive layers 604, the high-strength support layer 602 and the organic gas diffusion layer 601 are connected, and the organic gas diffusion layer 601 penetrates into the high-strength support layer 602 to form a permeable composite layer 603. Specifically, the organic gas diffusion layer 601 is made of polyimide; the high-strength support layer 602 is made of polyamide.

[0058] Specifically, the thickness of the organic gas diffusion layer 601 is 5 mm; the thickness of the high-strength support layer 602 is 5 mm; the thickness of the first adhesive layer 604A is 1 mm, and the thickness of the second adhesive layer 604B is 3 mm; the thickness of the permeable composite layer 603 accounts for 45% of the thickness of the high-strength support layer 602 .

[0059] Specifically, the adhesive layer 604 is used to bond the breathable membrane 6 to the support plate 5 .

[0060] Example 5

[0061] The difference between this embodiment and embodiment 1 is that, specifically, the thickness of the organic gas diffusion layer 601 is 0.1 mm; the thickness of the high-strength support layer 602 is 0.1 mm; the thickness of the adhesive layer 604 is 0.1 mm. The thickness of the permeable composite layer 603 accounts for 20% of the thickness of the high-strength support layer 602.

[0062] Example 6

[0063] The difference between this embodiment and embodiment 1 lies in the difference in the air permeable membrane 6 .

[0064] Please read further Figure 6 In this embodiment, the breathable membrane 6 is a five-layer structure, including a high-strength support layer 602, two organic gas diffusion layers 601 and two adhesive layers 604. The high-strength support layer 602 is arranged between the two organic gas diffusion layers 601, the high-strength support layer 602 and the organic gas diffusion layer 601 are arranged between the two adhesive layers 604, and the organic gas diffusion layer 601 penetrates into the high-strength support layer 602 to form a permeable composite layer 603. Specifically, the two organic gas diffusion layers 601 are made of polyimide; the high-strength support layer 602 is made of polyamide, and the two adhesive layers 604 are made of silicone.

[0065] Specifically, the thickness of the two organic gas diffusion layers 601 is 0.1 mm; the thickness of the high-strength support layer 602 is 0.1 mm; the thickness of the two adhesive layers 604 is 0.1 mm; and the thickness of the permeable composite layer 603 accounts for 100% of the thickness of the high-strength support layer 602 .

[0066] Example 7

[0067] The difference between this embodiment and embodiment 1 is that the thickness of the organic gas diffusion layer is 0.83 mm.

[0068] The use principle of the breathable membrane type lithium ion battery electrolyte standard leak of the present invention is as follows:

[0069] The electrolyte in the liquid storage chamber evaporates into gas, and the gas and liquid coexist in the liquid storage chamber. Place the breathable membrane type lithium ion battery electrolyte standard leak in the cavity of the mass spectrometer, evacuate the cavity, and under the pressure difference and the steady flow of the breathable steady flow component, the electrolyte gas in the liquid storage chamber evaporates into the cavity of the mass spectrometer at a stable rate and is detected by the mass spectrometer. The mass spectrometer calibrates, calibrates or inspects according to the detected electrical signal strength and the leakage rate of the breathable membrane type lithium ion battery electrolyte standard leak. When the standard leak exceeds the service life, after the electrolyte and other liquids in the liquid storage chamber have evaporated, open the sealing component of the injection port, add new electrolyte and other liquids into the liquid storage chamber with a syringe needle or other means, and then install the sealing component of the injection port, and the standard leak can be used again.

[0070] In order to illustrate the technical effect of the present invention, the stability test was carried out on the standard leaks of Examples 1-6.

[0071] Test method: Place the gas permeable membrane type lithium ion battery electrolyte standard leak of Examples 1-6 in the cavity of the mass spectrometer, evacuate the cavity, and allow the electrolyte gas in the liquid storage cavity to evaporate into the cavity of the mass spectrometer and be detected by the mass spectrometer. Test its leakage rate every ten minutes, and test each group 10 times. Then calculate the average value and variation index of each group. The specific results are shown in Table 1 below:

[0072] Table 1 Stability test results of Examples 1-6

[0073]

[0074]

[0075] As shown in Table 1, the average leakage rate of the electrolyte of the breathable membrane type lithium ion battery of the present invention can be maintained at 3×10 -7 -7×10 -4 mbar*L / s, and the variation index can be maintained within 15%, indicating that the breathable membrane type lithium ion battery electrolyte of the present invention has good standard leakage stability.

[0076] In order to explore the influence of the structure and material of the breathable membrane on the stability of the standard leakage, comparative examples 1-4 are set up based on example 1 as follows.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that the breathable membrane is a single-layer structure, the material is polypropylene (PP), and the thickness of the breathable membrane is 3.76 mm.

[0079] Comparative Example 2

[0080] The difference from Example 1 is that the breathable membrane is a single-layer structure, the material is a polyethylene film (PE film), and the thickness of the breathable membrane is 3.76 mm.

[0081] Comparative Example 3

[0082] The difference from Example 1 is that the breathable membrane is a single-layer structure, the material is polyurethane (TPU), and the thickness of the breathable membrane is 3.76 mm.

[0083] Comparative Example 4

[0084] The difference from Example 1 is that the breathable membrane is a single-layer structure, the material is polytetrafluoroethylene (PTEE), and the thickness of the breathable membrane is 3.76 mm.

[0085] The stability test of the standard leaks of Comparative Examples 1-4 and Example 1 was carried out in the same manner as in Examples 1-6. The test results are shown in Table 2 below. A comparison of the stability test results of Example 1 and Comparative Examples 1-4 is plotted based on the data in Table 2. Figure 7 shown.

[0086] Table 2 Stability test results of Example 1 and Comparative Examples 1-4

[0087]

[0088]

[0089] As shown in Table 2 and Figure 7 As shown, the coefficient of variation of the breathable membranes with other structures or materials used in the marking leak is much higher than that of the breathable membrane of the present application, that is, changing the structure and material of the breathable membrane of the present application will greatly reduce the stability of the marking leak. The data of Example 1 in Table 2 deviate from those in Table 1. This is because the same solution will fluctuate in two tests, which is a normal phenomenon.

[0090] In order to further verify the effect of the thickness of the breathable membrane on the stability of the standard leakage in the present invention, comparative examples 5 and 6 are set up based on embodiment 1 as follows.

[0091] Comparative Example 5

[0092] The difference from Example 1 is that the thickness of the organic diffusion layer is 0.006 mm.

[0093] Comparative Example 6

[0094] The difference from Example 1 is that the thickness of the organic diffusion layer is 5.5 mm.

[0095] The stability test of the standard leakage of comparative examples 5 and 6 and embodiment 1 was compared. The test method was the same as that of embodiments 1-6. The test results are shown in Table 3 below. A comparison chart of the stability test results of embodiment 1, comparative examples 5 and comparative examples 6 was drawn based on the data in Table 2. Figure 8 shown.

[0096] Table 3 Stability test results of Example 1 and Comparative Example 5 and Comparative Example 6

[0097]

[0098] As shown in Table 3 and Figure 8 As shown, when the thickness of the breathable membrane in the present application is changed, the coefficient of variation is greater than 10%, and the stability of the standard leakage becomes poor. In addition, when the thickness of the organic diffusion layer is lower than the range of the present application (Comparative Example 5), the average leakage rate is high; when the thickness of the organic diffusion layer is higher than the range of the present application (Comparative Example 6), the average leakage rate is low. Too high or too low a leakage rate affects the ventilation effect of the breathable membrane, thereby resulting in insufficient calibration accuracy. In addition, too high a leakage rate is prone to instrument contamination.

[0099] In addition, in order to further illustrate the long-term stability of the standard leakage of the breathable membrane type lithium ion battery electrolyte of the present invention, the standard leakage of Example 7 was tested for long-term stability. The test method was consistent with the test method of the above-mentioned Examples 1-6, and the test was continuously conducted for 39 days (2023.11.21-2024.01.05). The test results are shown in Table 3 below. The long-term stability test results are plotted according to the data in Table 3 as shown in FIG. Fig. 9 shown.

[0100] Table 3 Long-term stability test results of Example 7

[0101]

[0102]

[0103]

[0104]

[0105] As shown in Table 3 and Fig. 9 As shown, 4 days before use, it is in the leakage aging period, at which time the leakage rate is in a stable rising stage. After 4 days, the leakage value is very stable, and the daily coefficient of variation can be maintained below 5%. The above shows that the leakage standard of the present application has long-term stability, and can be used for calibration, calibration and spot inspection of leakage detection equipment to improve the accuracy of the detection results.

[0106] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A breathable membrane type lithium ion battery electrolyte leakage marker, characterized in that: It comprises a leak body and a breathable membrane, wherein the leak body is provided with a liquid storage cavity; the leak body is provided with a breathable port, and the liquid storage cavity is connected with the outside of the leak body through a flow stabilizing hole; the breathable flow stabilizing component is installed in the breathable port; the breathable membrane is a layered structure, and comprises a high-strength support layer and an organic gas diffusion layer; the organic gas diffusion layer penetrates into the high-strength support layer to form a permeable composite layer, and the thickness of the permeable composite layer accounts for 0-100% of the thickness of the high-strength support layer.

2. The gas permeable membrane type lithium ion battery electrolyte leakage mark according to claim 1, characterized in that: The organic gas diffusion layer is provided with two layers, and the high-strength support layer is located between the two layers of the organic gas diffusion layer.

3. The gas permeable membrane type lithium ion battery electrolyte leakage marker as claimed in claim 1, characterized in that: The breathable film further comprises an adhesive layer, and the adhesive layer is connected to the high-strength support layer; the high-strength support layer is located between the adhesive layer and the organic gas diffusion layer.

4. The gas permeable membrane type lithium ion battery electrolyte leakage mark as claimed in claim 3, characterized in that: The adhesive layer is provided with two layers, and the high-strength support layer and the organic gas diffusion layer are located between the two adhesive layers.

5. The gas permeable membrane type lithium ion battery electrolyte leakage marker according to any one of claims 1 to 4, characterized in that: The material of the organic gas diffusion layer is selected from one of perfluorosulfonic acid resin, polymethylpentene, polyimide and graphene oxide.

6. The gas permeable membrane type lithium ion battery electrolyte leakage mark as claimed in claim 5, characterized in that: The thickness of the organic gas diffusion layer is 0.01 mm-5 mm.

7. The gas permeable membrane type lithium ion battery electrolyte leakage marker according to any one of claims 1 to 4, characterized in that: The material of the high-strength support layer is selected from one of polyamide, polyolefin and polytetrafluoroethylene.

8. The gas permeable membrane type lithium ion battery electrolyte leakage mark according to claim 7, characterized in that: The high-strength supporting layer is 0.1mm-5mm.

9. The gas permeable membrane type lithium ion battery electrolyte leakage marker as claimed in claim 3 or 4, characterized in that: The material of the adhesive layer is selected from one of epoxy resin, silicone, fluorinated rubber and acrylic glue.

10. The gas permeable membrane type lithium ion battery electrolyte leakage marker according to claim 9, characterized in that: The thickness of the adhesive layer is 0.1mm-3mm.

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