Electrical strength test fixture device for lithium battery separator

Abstract

The utility model relates to lithium battery material detection technical field, concretely relates to a kind of electrical strength test fixture device for lithium battery diaphragm;Including upper electrode component, lower electrode component, positioning guide mechanism and safety protection rack;The upper electrode component, lower electrode component and positioning guide mechanism are all installed inside safety protection rack, the upper electrode component includes rigid conductive backplate, flexible conductive contact layer and the pressure self-adapting uniform distribution layer being arranged between rigid conductive backplate and flexible conductive contact layer;The lower electrode component is fixedly installed on the inner wall of safety protection rack lower end portion, the upper electrode component is placed directly above lower electrode component, the upper electrode component is flexible conductive contact layer, pressure self-adapting uniform distribution layer and rigid conductive backplate from bottom to top in turn, and the positioning guide mechanism is installed on upper electrode component upper end portion.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery material testing technology, specifically to an electrical strength testing fixture device for lithium battery separators. Background Technology

[0002] In the energy storage and safe operation of lithium batteries, the separator, as a key insulating material, directly determines the voltage withstand performance and safety of the lithium battery. Therefore, accurate electrical strength testing of lithium battery separators is a core step in the research and development, production, and quality inspection of lithium battery materials. Currently, the lithium battery separator electrical strength testing fixtures commonly used in the industry still have many technical defects in practical applications, making it difficult to meet the requirements of high-precision testing. The electrode structure design of existing testing fixtures is unreasonable, resulting in uneven contact between the electrodes and the separator and distorted electric field distribution, which seriously affects the authenticity and reliability of the test data. The upper electrode of traditional fixtures often uses a single rigid conductive material (such as a pure metal disk), the surface of which cannot adapt to the slight flatness deviations that the separator may have. When in contact with the separator, local "point contact" or "line contact" phenomena are prone to occur, and uniform surface contact cannot be formed. This uneven contact will directly cause disordered electric field distribution between electrodes, and abnormally high local electric field strength. Therefore, the measured separator breakdown strength is not the true performance of the separator material itself, but "false data" affected by local electric field distortion. Utility Model Content

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide an electrical strength testing fixture device for lithium battery separators.

[0004] The objective of this utility model can be achieved through the following technical solutions:

[0005] An electrical strength testing fixture for lithium battery separators includes an upper electrode assembly, a lower electrode assembly, a positioning and guiding mechanism, and a safety protection frame. The upper electrode assembly, lower electrode assembly, and positioning and guiding mechanism are all installed inside the safety protection frame. The upper electrode assembly includes a rigid conductive backplate, a flexible conductive contact layer, and a pressure-adaptive uniform distribution layer disposed between the rigid conductive backplate and the flexible conductive contact layer. The lower electrode assembly is fixedly installed on the inner wall of the lower end of the safety protection frame, and the upper electrode assembly is placed directly above the lower electrode assembly. The upper electrode assembly consists of, from bottom to top, a flexible conductive contact layer, a pressure-adaptive uniform distribution layer, and a rigid conductive backplate. The positioning and guiding mechanism is installed at the upper end of the upper electrode assembly.

[0006] Furthermore, the pressure-adaptive uniform distribution layer is a sealed cavity filled with insulating fluid; the flexible conductive contact layer is a 1mm thick conductive silicone plate with a surface resistivity <0.5Ω / sq and a Shore hardness of A40±5; the sealed cavity of the pressure-adaptive uniform distribution layer is formed by the flexible conductive contact layer, an annular fluororubber sealing ring, and a rigid conductive back plate, and the cavity is filled with insulating silicone oil with a thickness of 5mm and no air bubbles after filling; the insulating silicone oil has a viscosity of 500cSt and a breakdown strength >35kV / mm; the rigid conductive back plate is a 50mm diameter brass disc with a nickel-plated surface for oxidation prevention.

[0007] Furthermore, the lower electrode assembly is a rigid conductive metal plate, which is a brass disk with a diameter of 100mm, with nickel plating on the surface to prevent oxidation and a surface roughness Ra≤0.8μm.

[0008] Furthermore, the safety protection frame is a transparent acrylic panel on all four sides.

[0009] Furthermore, the positioning and guiding mechanism includes a threaded rigid conductive rod and an acrylic plate with a small hole in the center, wherein the threaded rigid conductive rod is rotatably connected to the acrylic plate with a small hole in the center.

[0010] Furthermore, the acrylic plate with a small hole in the center has a circular groove inside, and a circular piece is fixedly installed at the lower end of the threaded rigid conductive rod, the circular piece being adapted to the circular groove.

[0011] Furthermore, a cover plate is detachably installed on the upper end of the safety protection frame, and a threaded hole is provided in the middle of the cover plate. The threaded rigid conductive rod passes through the threaded hole and is adapted to the threaded hole.

[0012] Furthermore, in the positioning and guiding mechanism, the threaded rigid conductive rod is a threaded brass rod with a diameter of 20mm, and the diameter of the hole in the acrylic plate with a small hole in the center is 20mm.

[0013] The explanations of the nouns, conjunctions, or adjectives used in the above technical solutions are as follows:

[0014] Fixed connection: refers to a connection in which parts or components are fixed in place and there is no relative movement. It is divided into two types: detachable connection and non-detachable connection.

[0015] (1) Detachable connection: The components are fixed together using screws, splines, wedges, etc. This type of connection can be disassembled during maintenance without damaging the parts. However, the specifications of the connecting parts used must be correct (such as the length of the bolts, keys, wedges) and properly tightened.

[0016] (2) Non-removable connections: These mainly refer to welding, riveting, and tenon joints. Since disassembly requires forging, sawing, or oxyacetylene cutting for repair or replacement, the parts generally cannot be reused. At the same time, attention should be paid to process quality, technical inspection, and remedial measures (such as correction and polishing) during connection.

[0017] The beneficial effects of this utility model are:

[0018] This invention innovatively employs a three-layer structure for the upper electrode assembly: a flexible conductive contact layer, a pressure-adaptive uniform distribution layer, and a rigid conductive backplate. The layers are arranged from bottom to top in the order of "flexible contact - pressure uniform distribution - rigid support." The pressure-adaptive uniform distribution layer enables uniform pressure transmission, and together with the flexible conductive contact layer, it adheres tightly to the surface of the lithium battery separator. This avoids localized electric field distortion caused by uneven contact in traditional rigid electrodes, ensuring that the measured breakdown strength data accurately reflects the performance of the separator material, significantly reducing data dispersion and solving the problem of low reliability in existing fixture test results. The upper electrode assembly is precisely positioned above the lower electrode assembly, structurally ensuring accurate electrode alignment and further reducing electric field distribution deviations caused by electrode misalignment. This provides a stable and uniform electric field environment for electrical strength testing, improving the consistency and reliability of test data. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a cross-sectional view of the overall device according to an embodiment of the present invention;

[0021] Figure 2 This is a cross-sectional structural diagram of the upper electrode assembly in an embodiment of this utility model.

[0022] In the diagram: 1. Upper electrode assembly; 2. Lower electrode assembly; 3. Positioning and guiding mechanism; 4. Safety protection frame; 5. Rigid conductive backplate; 6. Flexible conductive contact layer; 7. Pressure adaptive uniform distribution layer; 8. Annular fluororubber sealing ring; 9. Threaded rigid conductive rod; 10. Acrylic plate with a small hole in the center; 11. Circular groove; 12. Circular piece; 13. Cover plate; 14. Threaded hole. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0024] An electrical strength testing fixture for lithium battery separators, such as Figures 1-2 As shown, the device includes an upper electrode assembly 1, a lower electrode assembly 2, a positioning and guiding mechanism 3, and a safety protection frame 4. The upper electrode assembly 1, the lower electrode assembly 2, and the positioning and guiding mechanism 3 are all installed inside the safety protection frame 4. The upper electrode assembly 1 includes a rigid conductive back plate 5, a flexible conductive contact layer 6, and a pressure adaptive uniform distribution layer 7 disposed between the rigid conductive back plate 5 and the flexible conductive contact layer 6. The lower electrode assembly 2 is fixedly installed on the inner wall of the lower end of the safety protection frame 4, and the upper electrode assembly 1 is placed directly above the lower electrode assembly 2. The upper electrode assembly 1 consists of, from bottom to top, the flexible conductive contact layer 6, the pressure adaptive uniform distribution layer 7, and the rigid conductive back plate 5. The positioning and guiding mechanism 3 is installed at the upper end of the upper electrode assembly 1.

[0025] The upper electrode assembly 1 comprises a three-layer structure consisting of a rigid conductive backplate 5, a pressure-adaptive uniform distribution layer 7, and a flexible conductive contact layer 6. From bottom to top, these layers are the flexible contact layer, the pressure-adaptive distribution layer, and the rigid backplate. This design allows for uniform pressure transmission through the pressure-adaptive layer, while the flexible contact layer ensures a tight fit with the diaphragm, preventing electric field distortion caused by uneven local pressure. Simultaneously, the upper electrode is precisely positioned directly above the lower electrode, further ensuring accurate electrode alignment and reducing test data dispersion caused by structural deviations, resulting in results that better reflect the electrical strength of the diaphragm itself. Both the upper and lower electrode assemblies 2 are integrated within the same rack, forming an independent and stable testing space. This prevents external environmental factors (such as airflow or foreign objects) from interfering with the contact state between the electrode and the diaphragm, ensuring a consistent testing environment and improving data accuracy. All core functional components (upper / lower electrodes, positioning and guiding mechanism 3) are installed inside a safety protection rack 4. This rack can prevent debris from splashing during testing (such as when the diaphragm is punctured by high pressure), reducing the risk of injury to operators. The enclosed rack structure also reduces external interference with the test, balancing safety and testing stability. The positioning and guiding mechanism 3 is installed on the upper end of the upper electrode assembly 1. It can directly cooperate with the lifting and alignment operation of the upper electrode without the need for an additional guiding structure. This simplifies the "aligning the electrode" step during sample loading, reduces operational difficulty, and improves testing efficiency. The lower electrode assembly 2 is fixed to the inner wall of the lower end of the frame, and the upper electrode assembly 1 is placed directly above it, forming a reasonable layout of "fixed at the bottom and movable at the top". This facilitates the placement / removal of the diaphragm and allows for precise control of the movement trajectory of the upper electrode through the positioning and guiding mechanism 3, preventing electrode displacement. At the same time, the rigid conductive back plate 5 provides stable support for the upper electrode, ensuring that the electrode structure does not deform during testing, which meets the structural stability requirements of high-voltage testing.

[0026] In a preferred embodiment of this utility model, the pressure-adaptive uniform distribution layer 7 is a sealed cavity filled with insulating fluid; the flexible conductive contact layer 6 is a conductive silicone plate with a thickness of 1 mm, a surface resistance of <0.5 Ω / sq, and a Shore hardness of A40±5; the sealed cavity of the pressure-adaptive uniform distribution layer 7 is formed by the flexible conductive contact layer 6, the annular fluororubber sealing ring 8, and the rigid conductive back plate 5, and the cavity is filled with insulating silicone oil with a thickness of 5 mm and no air bubbles after filling; the insulating silicone oil has a viscosity of 500 cSt and a breakdown strength of >35 kV / mm; the rigid conductive back plate 5 is a brass disc with a diameter of 50 mm and a nickel-plated surface for oxidation prevention. The pressure-adaptive uniform distribution layer 7 is a sealed cavity filled with insulating silicone oil. The 500cSt viscosity insulating silicone oil can flow with pressure to achieve uniform pressure transmission. Combined with a 1mm thick flexible conductive silicone plate with a Shore hardness of A40±5, it allows the upper electrode to adhere tightly to the membrane surface and the pressure distribution to be uniform, avoiding electric field distortion caused by uneven local pressure, reducing the dispersion of test data, and making the results more consistent with the breakdown strength of the membrane itself. The breakdown strength of the insulating silicone oil is >35kV / mm, which is much higher than the voltage required for conventional testing of lithium battery membranes, thus avoiding interference from the test due to the breakdown of the silicone oil itself. After the cavity is filled, there are no air bubbles, eliminating the problem of local electric field concentration caused by air bubbles, further ensuring the accuracy of the test. The rigid conductive backplate 5 is a 50mm diameter nickel-plated brass disk. Brass has excellent conductivity and nickel plating prevents oxidation, ensuring stable transmission of electrical signals and avoiding the impact of poor conductivity or oxidation of the backplate on the stability of the test circuit.

[0027] In a preferred embodiment of this invention, the lower electrode assembly 2 is a rigid conductive metal plate, which is a 100mm diameter brass disc with a nickel-plated surface for oxidation prevention and a surface roughness Ra≤0.8μm. The 100mm diameter brass disc provides ample and flat support for the lithium battery separator, preventing local wrinkles due to insufficient support area. Simultaneously, the high-precision smooth design with a surface roughness Ra≤0.8μm eliminates "contact dead angles" caused by uneven electrode surfaces, ensuring uniform contact between the electrode and the separator, preventing local electric field concentration, and thus reducing test data dispersion, making the measured electrical strength more consistent with the actual performance of the separator. Brass itself has excellent conductivity, and combined with the ample conductive cross-sectional area of ​​100mm diameter, it reduces resistance loss during current transmission, ensuring stable signal transmission between electrodes during testing. This avoids fluctuations in circuit parameters due to poor conductivity, affecting the reliability of the electrical strength test results and meeting the circuit stability requirements for lithium battery separator testing.

[0028] In a preferred embodiment of this invention, the positioning and guiding mechanism 3 includes a threaded rigid conductive rod 9 and an acrylic plate 10 with a central hole. The threaded rigid conductive rod 9 and the acrylic plate 10 with a central hole are rotatably connected. In the positioning and guiding mechanism 3, the threaded rigid conductive rod 9 is a threaded brass rod with a diameter of 20mm, and the diameter of the central hole in the acrylic plate 10 is 20mm. The diameters of the threaded rigid conductive rod 9 and the central hole in the acrylic plate are both 20mm, ensuring a perfect size match and a tight fit. This "equal diameter design" limits the radial offset of the upper electrode assembly 1 during its vertical movement, ensuring that the upper electrode is always precisely aligned with the lower electrode, avoiding uneven electric field distribution due to electrode misalignment, thereby reducing test data dispersion and improving the reliability of test results. The threaded rigid conductive rod 9 is made of brass, which has excellent conductivity. The 20mm diameter design ensures sufficient conductive cross-sectional area, reduces resistance loss during current transmission, and ensures stable transmission of electrical signals between electrodes during testing. This avoids affecting the accuracy of electrical strength testing due to poor conductivity (meeting the requirements for circuit stability in lithium battery separator electrical strength testing).

[0029] In a preferred embodiment of this utility model, a cover plate 13 is detachably installed on the upper end of the safety protection frame 4. A threaded hole 14 is provided in the middle of the cover plate 13, through which the threaded rigid conductive rod 9 passes, and the threaded rigid conductive rod 9 is adapted to the threaded rod. The cover plate 13 adopts a detachable design. When placing the lithium battery separator before testing or removing the sample after testing, the cover plate 13 can be directly removed, providing sufficient space for operation between the upper electrode assembly 1 and the lower electrode assembly 2, avoiding obstruction of sample handling by the fixed cover plate 13, and greatly reducing the difficulty of sample loading. At the same time, when cleaning, repairing or replacing the upper electrode assembly 1, positioning guide mechanism 3, etc. inside the device, the detachable cover plate 13 can also simplify maintenance steps and reduce operation time. The threaded hole 14 in the middle of the cover plate 13 is adapted to the threaded rigid conductive rod 9 to form a threaded transmission structure. By rotating the threaded rigid conductive rod 9, the precise transmission characteristics of the thread allow for the smooth and slow raising and lowering of the upper electrode assembly 1. This avoids uneven force or positional misalignment caused by manual adjustment of the upper electrode, ensuring that the upper electrode remains coaxially aligned with the lower electrode. This prevents distortion of the electric field distribution caused by electrode misalignment, thus guaranteeing the consistency and reliability of the test data. The self-locking property of the threaded drive allows the upper electrode assembly 1 to be stably fixed after reaching the target position, preventing the upper electrode from shifting or deviating due to vibration or external interference during the test. This ensures a constant contact pressure between the electrode and the diaphragm, eliminating the impact of pressure fluctuations on the electrical strength test results.

[0030] In a preferred embodiment of this invention, the acrylic plate 10 with a central hole has a circular groove 11 inside. A circular plate 12 is fixedly installed at the lower end of the threaded rigid conductive rod 9, and the circular plate 12 is adapted to the circular groove 11. The adaptation structure of the circular plate 12 and the circular groove 11 can separate the "rotational movement" of the threaded rigid conductive rod 9 from the "axial lifting movement" of the upper electrode assembly 1: when the operator rotates the conductive rod, the circular plate 12 only rotates within the circular groove 11 and does not drive the upper electrode assembly 1 to rotate synchronously; at the same time, the axial thrust of the conductive rod is transmitted to the acrylic plate through the circular plate 12, thereby driving the upper electrode assembly 1 to lift smoothly. This design avoids the upper electrode from twisting when the conductive rod rotates, preventing frictional damage between the upper electrode and the diaphragm, and also avoids electrode misalignment caused by twisting, ensuring that the upper electrode and the diaphragm always maintain parallel and uniform contact, and ensuring a stable electric field distribution during the test.

[0031] As a preferred embodiment of this utility model, the safety protection frame 4 is a four-sided transparent acrylic plate. The acrylic plate possesses sufficient mechanical strength to prevent diaphragm fragments from flying during testing (such as during high-voltage breakdown), thus avoiding injury to operators. Simultaneously, its transparency ensures that operators can observe the contact state between the electrodes and the diaphragm in real time, as well as any abnormal phenomena during the test (such as localized breakdown points), facilitating timely assessment of test validity. The acrylic plate is an insulating material and will not cause electrical interference with the upper and lower electrode assemblies 1 / 2 (made of brass, conductive), preventing the frame's conductivity from affecting the stability of the test circuit, ensuring the accuracy of electrical strength test data, and meeting the insulation environment requirements for lithium battery material testing. The four-sided transparent structure provides no visual obstruction, allowing operators to confirm the diaphragm's centered position and the electrodes' precise alignment from multiple angles during sample loading (by placing the diaphragm and aligning the electrodes using the positioning guide mechanism 3), reducing the risk of sample loading deviation. It also facilitates rapid post-test inspection of the diaphragm's condition, improving overall testing efficiency.

[0032] Working principle and usage process of this utility model:

[0033] During use, the lithium battery separator to be tested is first placed on the lower electrode assembly 2. The upper electrode assembly 1 is precisely aligned with the lower electrode assembly 2 via the acrylic plate 10 with a small central hole and the threaded rigid conductive rod 9 in the positioning and guiding mechanism 3, completing the sample loading. Subsequently, during testing, the pressure adaptive uniform distribution layer 7 in the upper electrode assembly 1 achieves uniform pressure distribution through the flow of internal insulating silicone oil. Combined with the flexible conductive contact layer 6, this ensures uniform contact between the upper electrode assembly 1 and the lithium battery separator, forming an ideal electric field distribution. Simultaneously, the design of the flexible conductive contact layer 6 reduces the risk of mechanical damage to the separator. The safety protection frame 4 uses four transparent acrylic plates, providing both safety protection and facilitating operator observation of the testing process. After testing, the tested separator is removed, and the next test can be performed.

[0034] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," 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.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims of this utility model.

Claims

1. A fixture for testing the electrical strength of lithium battery separators, characterized in that, The device includes an upper electrode assembly (1), a lower electrode assembly (2), a positioning guide mechanism (3), and a safety protection frame (4). The upper electrode assembly (1), the lower electrode assembly (2), and the positioning guide mechanism (3) are all installed inside the safety protection frame (4). The upper electrode assembly (1) includes a rigid conductive back plate (5), a flexible conductive contact layer (6), and a pressure adaptive uniform distribution layer (7) disposed between the rigid conductive back plate (5) and the flexible conductive contact layer (6). The lower electrode assembly (2) is fixedly installed on the inner wall of the lower end of the safety protection frame (4). The upper electrode assembly (1) is placed directly above the lower electrode assembly (2). The upper electrode assembly (1) consists of a flexible conductive contact layer (6), a pressure adaptive uniform distribution layer (7), and a rigid conductive back plate (5) from bottom to top. The positioning guide mechanism (3) is installed at the upper end of the upper electrode assembly (1).

2. The electrical strength testing fixture device for lithium battery separators according to claim 1, characterized in that, The pressure-adaptive uniform distribution layer (7) is a sealed cavity filled with insulating fluid. The flexible conductive contact layer (6) is a conductive silicone plate with a thickness of 1 mm, a surface resistance of <0.5 Ω / sq, and a Shore hardness of A40±5. The sealed cavity of the pressure-adaptive uniform distribution layer (7) is surrounded by the flexible conductive contact layer (6), an annular fluororubber sealing ring (8), and a rigid conductive back plate (5). The cavity is filled with insulating silicone oil with a thickness of 5 mm and no air bubbles after filling. The insulating silicone oil has a viscosity of 500 cSt and a breakdown strength of >35 kV / mm. The rigid conductive back plate (5) is a brass disc with a diameter of 50 mm and a nickel-plated surface to prevent oxidation.

3. The electrical strength testing fixture device for lithium battery separators according to claim 1, characterized in that, The lower electrode assembly (2) is a rigid conductive metal plate, which is a brass disk with a diameter of 100mm, with nickel plating on the surface to prevent oxidation and a surface roughness Ra≤0.8μm.

4. The electrical strength testing fixture device for lithium battery separators according to claim 1, characterized in that, The safety protection frame (4) is a transparent acrylic sheet on all four sides.

5. The electrical strength testing fixture device for lithium battery separators according to claim 1, characterized in that, The positioning and guiding mechanism (3) includes a threaded rigid conductive rod (9) and an acrylic plate (10) with a small hole in the center. The threaded rigid conductive rod (9) is rotatably connected to the acrylic plate (10) with a small hole in the center.

6. The electrical strength testing fixture device for lithium battery separators according to claim 5, characterized in that, The acrylic plate (10) with a small hole in the center has a circular groove (11) inside. A circular piece (12) is fixedly installed at the lower end of the threaded rigid conductive rod (9). The circular piece (12) is adapted to the circular groove (11).

7. The electrical strength testing fixture device for lithium battery separators according to claim 5, characterized in that, The upper end of the safety protection frame (4) is detachably equipped with a cover plate (13). A threaded hole (14) is provided in the middle of the cover plate (13). The threaded rigid conductive rod (9) passes through the threaded hole (14) and is adapted to the threaded hole (14).

8. The electrical strength testing fixture device for lithium battery separators according to claim 5, characterized in that, In the positioning and guiding mechanism (3), the threaded rigid conductive rod (9) is a threaded brass rod with a diameter of 20mm, and the diameter of the hole in the acrylic plate (10) with a small hole in the center is 20mm.

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