Seal, battery cover plate, battery, and electric device

Abstract

The application relates to the technical field of batteries, in particular to a sealing element, a battery cover plate, a battery and an electric device, the sealing element comprising: a main body, the main body being provided with a convex part, and the main body comprising a helium absorption material; and a rubber plug, the rubber plug being arranged on one side of the main body provided with the convex part, and the convex part being embedded in the rubber plug. The sealing element can greatly improve the back pressure helium leak detection rate, improve the problem of missed detection, and improve the detection accuracy.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to seals, battery covers, batteries, and electrical devices. Background Technology

[0002] Currently, all commercially available batteries use electrolyte as the electrolyte. During the manufacturing process, an injection hole is pre-drilled in the outer packaging for injecting the electrolyte. This injection hole is typically sealed with a plastic flat nail. A sealing cap is then placed on the injection hole step above the plastic flat nail, and the sealing cap is laser welded to the battery cover. After the sealing cap is welded to the injection hole step, an external seal is formed over the plastic flat nail. (See the structural diagram below.) Figure 1 When defects (such as holes) occur in the welded area, moisture or oxygen in the air may corrode the rubber stopper of the plastic flat nail, causing the electrolyte to leak out of the battery cell through the corroded rubber stopper, thus posing a safety risk to the battery cell or the package containing the battery cell.

[0003] To detect welding defects in the sealing weld area, the back-pressure helium sampling method is currently used to inspect the weld seal. However, this method is prone to missing defects when there are large holes in the sealing weld area. Therefore, the relevant technology still needs improvement. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a seal, battery cover, battery, and electrical device that can effectively improve the accuracy of back pressure helium detection.

[0005] In a first aspect of this application, a sealing element is provided. According to an embodiment of this application, the sealing element includes: a body having a protrusion, the body comprising a helium-absorbing material; and a rubber stopper located on the side of the body where the protrusion is located, the protrusion being embedded in the rubber stopper. Thus, the helium-absorbing material in the body has a strong helium adsorption capacity, which can improve the leakage rate of back pressure helium detection when the weld has large or ultra-large pores, thereby improving the leakage detection problem and effectively increasing the accuracy of back pressure helium detection.

[0006] According to an embodiment of this application, the main body includes a matrix and the helium-absorbing material, the helium-absorbing material is dispersed in the matrix, and the helium adsorption capacity of the helium-absorbing material is greater than the helium adsorption capacity of the matrix; or the main body is composed of the helium-absorbing material.

[0007] According to an embodiment of this application, the main body includes a cap and a protrusion connected to the cap, wherein the helium-absorbing material is located at least in the cap.

[0008] According to an embodiment of this application, the mass ratio of the matrix to the helium-absorbing material is 1:5 to 10.

[0009] According to embodiments of this application, the matrix includes at least one of polyphenylene sulfide, polyethylene terephthalate, acrylonitrile-butadiene-styrene, polycarbonate, polyamide, polybutylene terephthalate, polyoxymethylene, and polyphenylene sulfide.

[0010] According to embodiments of this application, the helium-absorbing material includes at least one of activated carbon powder, alumina powder, silicon oxide powder, and silica gel.

[0011] According to an embodiment of this application, the D50 particle size of the helium-absorbing material is 5.0 μm to 15 μm.

[0012] According to an embodiment of this application, the specific surface area of ​​the helium-absorbing material is 200 m². 2 / g~1300m 2 / g.

[0013] In a second aspect, this application provides a battery cover. According to an embodiment of this application, the battery cover includes: a cover body having a liquid injection hole; and the aforementioned sealing member, which is interference-fitted into the liquid injection hole. It is understood that, with the aforementioned sealing member, the battery cover has a lower back pressure helium detection failure rate.

[0014] In a third aspect, this application provides a battery. According to an embodiment of this application, the battery includes the battery cover described above. This battery possesses all the features and advantages of the battery cover described above, which will not be repeated here.

[0015] In a fourth aspect, this application provides an electrical device. According to an embodiment of this application, the electrical device includes the battery described above. This electrical device possesses all the features and advantages of the battery described above, which will not be repeated here. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the sealing nail for sealing the liquid injection hole of the battery cover.

[0017] Figure 2 This is a schematic diagram illustrating the principle of back pressure helium detection.

[0018] Figure 3 This is a schematic diagram of the structure of a sealing element according to an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of the structure of a battery cover plate according to an embodiment of this application.

[0020] Figure label:

[0021] 11: Sealing cap 12: Sealing nail 121: Protrusion 13: Battery cover 14: Injection hole 15: Weld 16: Sealed space 21: Sealing cap 22: Sealing nail 23: Battery cover 25: Weld 26: Sealed space 27: Sealing head 28: Sealing ring 29: Sealed space 201, 203: Mechanical pump 202: Helium compression unit 204: Vacuum gauge 205: Detection unit A, B, C, D: Vacuum valve 31: Main body 311: Protrusion 32: Rubber stopper 312: Cap 40: Cover body 41: Injection hole 42: Seal 421: Rubber stopper 43: Sealing cap Detailed Implementation

[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] This application is based on the inventor's following discoveries and understandings:

[0024] In commonly used batteries, the welding of the sealing cap above the sealing nail directly affects the risk of leakage. Therefore, it is necessary to inspect the welding sealing area for defects during the production process. Currently, to detect welding defects, a back-pressure helium testing method is used to inspect the weld's seal. The testing principle is as follows: if a defect (leak) exists in the weld, helium gas is first forced into the sealed space 1 at a certain pressure in the helium pressurization station. Then, the helium gas in the sealed space 26 is tested at the helium testing station, and the leakage rate (leakage rate) from the weld leak is used to determine the quality of the sealing weld. The specific process is as follows: Figure 2As shown, the battery is first moved to the helium compression station. After the sealing ring on the sealing head covers (avoiding the weld seam) the sealing cap on the injection hole, vacuum valve A is opened and vacuum valve B is closed. Mechanical pump 201 evacuates the sealed space 29. After reaching the set pressure, vacuum valve A closes and vacuum valve B opens, injecting a certain amount of helium into the sealed space 29 through the helium compression unit. If there are holes in the sealing weld seam at this time, the helium in the sealed space 29 will enter the sealed space 26 through pressure. If there are no holes in the weld seam, no helium will enter the sealed space 26. After helium compression is completed, the battery is transferred to the helium inspection station. Vacuum valve C is opened first, and mechanical pump 203 evacuates the sealed spaces 29 and 26 (assuming there are holes in the weld). Once a certain vacuum level is reached, vacuum valve C closes, and vacuum valve D (detection valve) opens. Helium gas in sealed space 26 escapes into sealed space 29 and is detected by detection unit (e.g., mass spectrometer) 205 through detection valve D. The leak rate is calculated and compared with the standard leak rate (also known as the upper limit of the acceptable weld leak rate standard, such as 3.0E-6 mbar·L / S). If the helium leak rate is less than the standard leak rate, the sealing weld is considered acceptable (OK). If the helium leak rate is greater than or equal to the standard leak rate, the sealing weld is considered unacceptable (NG).

[0025] In actual helium leak detection, as the pores in the weld increase from small to large, the back pressure helium leak detection first increases to reach its maximum peak value, and then gradually decreases. When the pores in the weld are large or extremely large, the back pressure helium leak detection rate is less than the standard leak rate, and at this time, a missed detection will occur.

[0026] To address the aforementioned issues to some extent, the inventors of this application discovered through research that adding a material with strong helium absorption capacity to the sealing nail can improve the helium leak detection rate when there are large or ultra-large pores in the weld, thus mitigating the problem of missed detection and increasing the accuracy of back pressure helium detection.

[0027] In view of this, a sealing element is provided in the first aspect of this application. According to an embodiment of this application, referring to... Figure 3 The sealing element includes: a body 31 with a protrusion 311, the body 31 containing a helium-absorbing material; and a rubber stopper 32 located on the side of the body 31 where the protrusion 311 is located, the protrusion 311 being embedded in the rubber stopper 32. Thus, the helium-absorbing material in the body has a strong helium adsorption capacity, which can improve the leakage rate of back pressure helium detection when the weld has large or ultra-large pores, thereby improving the leakage detection problem and effectively increasing the accuracy of back pressure helium detection.

[0028] It is understandable that there are no particular restrictions on the specific way the helium-absorbing material is placed in the main body. For example, the helium-absorbing material can be placed only in a part of the main body, or it can be placed in the entire main body, or the entire main body can be made of helium-absorbing material.

[0029] In some embodiments, the main body includes a matrix and the helium-absorbing material, wherein the helium-absorbing material is dispersed in the matrix, and the helium adsorption capacity of the helium-absorbing material is greater than that of the matrix. This can effectively improve the accuracy of backpressure helium detection when the weld has large or ultra-large pores.

[0030] In some embodiments, reference is made to Figure 3 The main body 31 includes a cap 312 and a protrusion 311 connected to the cap 312, with the helium-absorbing material located at least within the cap 312. Specifically, the protrusion is embedded in the rubber stopper 32 and cannot come into contact with helium gas during backpressure helium detection. Therefore, helium-absorbing material can be placed only in the cap, which also has a good effect on improving the backpressure helium leak detection rate.

[0031] In some embodiments, the mass ratio of the matrix to the helium-absorbing material is 1:5 to 10, such as 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc. Specifically, when the amount of helium-absorbing material is small, the proportion of matrix raw materials is too high, resulting in poor helium storage capacity of the main body and the possibility of missed detection. When the amount of helium-absorbing material is too high, the excessive proportion of helium-absorbing material may cause the main body to be poorly formed or have low mechanical strength during the preparation process, failing to meet the performance requirements of the seal. However, when the ratio of the matrix to the helium-absorbing material is within the above-mentioned range, both the improvement of helium absorption capacity and the strength requirements of the seal can be achieved, resulting in better performance.

[0032] In some embodiments, the matrix may include at least one of polyphenylene sulfide, polyethylene terephthalate, acrylonitrile-butadiene-styrene, polycarbonate, polyamide, polybutylene terephthalate, polyoxymethylene, and polyphenylene sulfide. Therefore, the seal has superior performance, is easy to process, uses widely available materials, and is relatively inexpensive.

[0033] In some embodiments, the helium-absorbing material may include at least one of activated carbon powder, alumina powder, and silica powder. Therefore, it exhibits superior helium absorption performance, good compatibility with the matrix, and is widely available and inexpensive.

[0034] In some embodiments, the D50 particle size of the helium-absorbing material is 5.0 μm to 15 μm, specifically such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc.

[0035] In some embodiments, the specific surface area of ​​the helium-absorbing material is 200 m². 2 / g~1300m 2 / g, specifically 200m 2 / g、300m 2 / g、400m 2 / g、500m 2 / g、600m 2 / g、700m 2 / g、800m 2 / g、900m 2 / g, 1000m 2 / g、1100m 2 / g、1200m 2 / g、1300m 2 / g etc.

[0036] Specifically, within the aforementioned particle size range, the adsorbent material possesses a suitable specific surface area, a large contact area with helium, strong helium adsorption capacity, and better compatibility with the matrix. It is also easy to injection mold, and the resulting seal has suitable mechanical strength. If the particle size of the helium-adsorbing material is too large, its specific surface area is relatively small, potentially reducing its helium adsorption capacity and compatibility with the matrix, increasing the difficulty of preparation, and possibly decreasing the overall mechanical strength and helium adsorption capacity. Conversely, if the particle size is too small, the specific surface area increases, enhancing the helium adsorption capacity. However, during preparation, there is a risk of the material being encapsulated by the matrix, leading to a decrease in the final product's helium adsorption capacity.

[0037] In some embodiments, the main body is composed of the helium-absorbing material. This further improves the accuracy of backpressure helium detection.

[0038] In some embodiments, the helium-absorbing material can be silica gel. This results in better helium absorption performance, which is beneficial for improving the accuracy of backpressure helium detection.

[0039] It is understood that the sealing element described in the embodiments of this application is used to seal the liquid injection hole in the battery cover, and its specific shape can be configured to match the shape of the liquid injection hole. In some embodiments, the sealing element may include, but is not limited to, sealing nails.

[0040] A second aspect of this application provides a battery cover. According to an embodiment of this application, referring to... Figure 4 The battery cover includes: a cover body 40, on which a liquid injection hole 41 is provided; and the aforementioned sealing element 42, which is interference-fitted into the liquid injection hole 41. It can be understood that, with the aforementioned sealing element, the back pressure helium detection of this battery cover has a low failure rate.

[0041] In a third aspect, this application provides a battery. According to an embodiment of this application, the battery includes the battery cover described above. This battery possesses all the features and advantages of the battery cover described above, which will not be repeated here.

[0042] It is understood that there are no other restrictions on the specific type of battery, such as including but not limited to lithium-ion batteries, sodium-ion batteries, etc., and the battery can be a prismatic battery, a pouch battery, a cylindrical battery, etc., and can be in different forms such as a battery cell, a battery module, or a battery pack.

[0043] It can also be understood that the battery may include the structures and components necessary for other conventional batteries. Taking a lithium-ion battery as an example, it may include an outer packaging, and an electrode assembly and electrolyte contained within the outer packaging. The electrode assembly may include a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes.

[0044] As an example, the positive electrode sheet may include a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, wherein the positive electrode film layer generally contains a positive active material, a conductive agent, and a binder. The negative electrode sheet may include a negative current collector and a negative electrode film layer located on at least one side of the negative current collector, wherein the negative electrode film layer generally contains a negative active material, a conductive agent, and a binder. The separator may be a single-layer or multi-layer polymer separator (including but not limited to polyethylene separators, polypropylene separators, polyethylene-polypropylene composite separators, etc.). The electrolyte generally includes an electrolyte salt and a solvent. The aforementioned positive active material, binder, conductive agent, current collector, electrolyte salt, and solvent can all be selected with reference to conventional techniques, and this application does not impose any particular limitations.

[0045] In a fourth aspect, this application provides an electrical device. According to an embodiment of this application, the electrical device includes the battery described above. This electrical device possesses all the features and advantages of the battery described above, which will not be repeated here.

[0046] According to embodiments of this application, the electrical device may include mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto. The battery may be used as a power source for the electrical device or as an energy storage unit for the electrical device.

[0047] It is understandable that, in addition to the battery mentioned above, the electrical device may also include the necessary structures and components of a conventional electrical device. Taking an electric vehicle as an example, it may include the body, windows, chassis, engine, seats, tires, and other necessary structures and components, which will not be elaborated here.

[0048] The embodiments of this application are described in detail below.

[0049] The seals in the following embodiments and comparative examples were prepared according to the following method, and the different parameters are shown in Table 1 below:

[0050] The matrix is ​​made of PPS (polyphenylene sulfide) or PET (polyethylene terephthalate), and the helium-absorbing material is made of activated carbon powder or alumina powder. The D50 particle size of the activated carbon powder is 10.0±1.0μm, and the specific surface area is 1100m². 2 / g; the D50 particle size of the alumina powder is 8.0±1.0μm, and the specific surface area is 260m². 2 / g~300m 2 / g; 10 sealant nails were made for each embodiment.

[0051] The specific preparation process is as follows: the matrix material and helium-absorbing material are mixed in a certain proportion to form a mixed material, and then injection molded to form the plastic head of the sealing nail (i.e. the main body of the sealing component). The injection pressure is 120 bar to 200 bar and the injection temperature is 250°C to 400°C.

[0052] Performance testing:

[0053] 1. Appearance of the seal: If the surface of the plastic head is smooth, without burrs or powder after injection molding, the appearance is good and is marked as OK; if the surface of the plastic head is pitted, or has burrs, or shows powder shedding, the appearance is poor and is marked as NG.

[0054] 2. Back pressure helium test: After the prepared plastic head is fitted with a rubber stopper, it is inserted into the battery's filling hole. The sealing cap is not welded (equivalent to the weld having the largest hole). The back pressure helium test method is used directly to detect its leakage rate. The test leakage rate value of each sealing nail is the average of 10 samples.

[0055] The helium leak detection method is as follows: if the helium leak rate is ≤3.0E-06, it indicates good welding and is recorded as OK; otherwise, it indicates poor welding and is recorded as NG.

[0056] The performance test results are shown in Table 1 below.

[0057] Table 1

[0058] Example The weight ratio of the matrix to the helium-absorbing material Helium leak detection rate Plastic head appearance Helium detection determination Remark Example 1 PPS: Activated Carbon Powder = 1:5 6.52E-06 OK NG Example 2 PPS: Activated Carbon Powder = 1:7 4.47E-05 OK NG Example 3 PPS: Activated Carbon Powder = 1:10 9.36E-05 OK NG Example 4 PET: Activated Carbon Powder = 1:5 5.43E-06 OK NG Example 5 PET: Activated Carbon Powder = 1:7 4.80E-05 OK NG Example 6 PET: Activated Carbon Powder = 1:10 8.60E-05 OK NG Example 7 PPS: Alumina powder = 1:7 4.80E-05 OK NG Example 8 PET:alumina powder = 1:7 4.36E-05 OK NG Comparative Example 1 PPS (All) 1.53E-06 OK OK Missed judgment Comparative Example 2 PET (all) 2.23E-06 OK OK Missed judgment

[0059] Based on the above test results, it can be seen that adding helium-absorbing material to the matrix can effectively improve the leak rate of back pressure helium detection and improve the problem of missed detection.

[0060] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0061] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0062] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A sealing element, characterized in that, include: The main body has protrusions and includes a matrix and a helium-absorbing material. The helium-absorbing material is dispersed in the matrix, and the helium adsorption capacity of the helium-absorbing material is greater than that of the matrix. A rubber stopper, wherein the rubber stopper is located on the side of the main body where the protrusion is provided, and the protrusion is embedded in the rubber stopper; The mass ratio of the matrix to the helium-absorbing material is 1:5~10; The matrix includes at least one of polyphenylene sulfide, polyethylene terephthalate, acrylonitrile-butadiene-styrene, polycarbonate, polyamide, polybutylene terephthalate, polyoxymethylene, and polyphenylene sulfide. The helium-absorbing material includes at least one of activated carbon powder, alumina powder, silicon dioxide powder, and silica gel.

2. The seal according to claim 1, characterized in that, The main body includes a cap and a protrusion connected to the cap, wherein the helium-absorbing material is located at least in the cap.

3. The seal according to claim 1 or 2, characterized in that, The helium-absorbing material has a D50 particle size of 5.0 μm to 15 μm.

4. The seal according to claim 1 or 2, characterized in that, The specific surface area of ​​the helium-absorbing material is 200 m². 2 / g~1300 m 2 / g.

5. A battery cover, characterized in that, include: A cover plate body, wherein an injection hole is provided on the cover plate body; The sealing element according to any one of claims 1 to 4, wherein the sealing element is interference-fitted into the injection hole.

6. A battery, characterized in that, Includes the battery cover as described in claim 5.

7. An electrical device, characterized in that, Includes the battery as described in claim 6.

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