An online testing device and method for the air permeability of lithium battery separators

Abstract

The application relates to the technical field of lithium battery diaphragm detection, and particularly discloses a lithium battery diaphragm air permeability online detection equipment and a detection method thereof, which comprises a first mounting frame, an upper detection box and a lower detection box are arranged on the first mounting frame, an air inlet is formed in the upper detection box, detection devices are arranged on the upper detection box and the lower detection box, a second mounting frame is arranged on the first mounting frame, and an adjusting assembly is arranged on the second mounting frame. The gas is input into the upper detection box through the air inlet, and the gas penetrates the diaphragm and enters the lower detection box. The detection device in the application can split the gas, the gas penetrates the diaphragm in different regions, whether there is air permeability defect in the corresponding region is judged through the gas penetrating the diaphragm in different regions, the region with the defect is marked by the detection device, material waste is reduced, the tension of the diaphragm itself is adjusted by the adjusting assembly, the stress state under the real working condition is restored, and the airflow path unevenness caused by the wrinkles or local relaxation is avoided.

Description

Technical Field

[0001] This application relates to the field of lithium battery separator testing technology, and in particular to an online testing device and method for the air permeability of lithium battery separators. Background Technology

[0002] The permeability of a lithium battery separator refers to the ease with which gas or ions can pass through the microporous structure of the separator. It is usually quantified by the Gurley value, which represents the time required for a certain volume of gas to pass through a unit area of ​​the separator under standard pressure difference. Its core function is to balance ion transport efficiency and safety. Too low permeability will lead to increased resistance to lithium ion migration, increase the internal resistance of the battery and reduce the charge and discharge rate, while too high permeability may cause the microporous structure to loosen, weaken the mechanical strength and increase the risk of lithium dendrite penetration.

[0003] In existing technologies, the gas permeability of lithium battery separators is generally tested using a gas differential pressure flow detection device. The core of this device includes a sealed test chamber, a precision pressure control system, a gas flow meter, and a timing module. The sealed test chamber includes upper and lower clamping plates. During operation, the separator roll is first cut into a separator sample of appropriate length, and then the separator sample is fixed between the upper and lower clamping plates. A constant pressure differential is maintained by the precision pressure control system. The gas flow meter and timing module are used to determine the time it takes for the gas to completely penetrate the separator, or the amount of gas that penetrates the separator per unit time, to determine whether the gas permeability of the tested separator is within the allowable error range of the specification value.

[0004] Regarding the aforementioned technologies, the upper and lower clamps hold and test the entire diaphragm sample. If the air permeability is unqualified, the defective area of ​​the diaphragm sample cannot be found, and the entire diaphragm sample will be wasted. It is also cumbersome to cut the diaphragm roll into diaphragm samples of appropriate length and then test each diaphragm sample one by one. Furthermore, it is impossible to test diaphragm samples under different tensions. Therefore, an improvement is proposed. Summary of the Invention

[0005] In order to continuously detect the membrane under different tensions and locate the defect area of ​​the membrane, this application provides an online detection device and method for the air permeability of lithium battery membranes.

[0006] This application provides an online testing device for the air permeability of lithium battery separators, which adopts the following technical solution:

[0007] An online testing device for the air permeability of lithium battery separators includes a first mounting frame, on which an upper testing box and a lower testing box are mounted. The upper testing box is vertically positioned directly above the lower testing box. When the upper and lower testing boxes are in contact, they clamp the separator. An air inlet is provided on the upper testing box. Both the upper and lower testing boxes are equipped with testing devices for blowing air into the separator in sections through the air inlet, performing air permeability testing in sections, and marking areas with air permeability defects. A second mounting frame is mounted on the first mounting frame, and two sets of the second mounting frames are provided. The two sets of the second mounting frames are symmetrically arranged on both sides of the lower testing box. An adjustment component is provided on the second mounting frame for adjusting the tension of the separator to be tested and for continuously moving the separator to achieve uninterrupted air permeability testing.

[0008] By adopting the above technical solution, the diaphragm is placed between the upper and lower detection boxes, and the upper and lower detection boxes are tightly sealed. Gas is then introduced into the upper detection box through the air inlet, creating a stable air pressure inside the upper detection box. Under the action of air pressure, the gas will penetrate the diaphragm and enter the lower detection box. During this process, the detection device of this application can divert the gas, allowing the gas to penetrate the diaphragm in different areas. The device can also determine whether there are permeability defects in the corresponding areas by observing the gas passing through the diaphragm in different areas. If permeability defects are found, the detection device can mark the defective areas so that the staff can analyze the defective areas, find the cause of the defects, and also cut the defective areas and perform adaptive processing on the remaining intact parts to reduce the waste of diaphragm material. In addition, during the use of the battery after electrolyte filling, the temperature rise of the battery will cause the diaphragm to experience a high-temperature environment. Therefore, this application can also adjust the temperature of the input gas and test the permeability of the diaphragm at different temperatures, thereby avoiding the situation where the diaphragm has unqualified permeability due to temperature changes.

[0009] During battery assembly, the separator is usually subjected to mechanical stress generated by winding or lamination. Its microporous structure may change due to relaxation or deformation, resulting in changes in pore size, porosity and distribution. If appropriate tension is not applied during testing, it will affect the accuracy of the air permeability test of the separator. Therefore, in order to improve the accuracy of the test, the adjustment component in this application can adjust the tension of the separator itself, restoring the stress state under real working conditions, making the air permeability test structure more practical and authoritative. At the same time, adjusting the tension of the separator also avoids the influence of uneven airflow path caused by wrinkles or local relaxation on the air permeability test.

[0010] Optionally, the detection device includes an upper transverse partition plate, an upper longitudinal partition plate, a lower transverse partition plate, a lower longitudinal partition plate, a driving mechanism, and a marking assembly. Multiple sets of the upper transverse partition plate and the upper longitudinal partition plate are provided. Multiple sets of the upper transverse partition plate are spaced apart within the upper detection box. Multiple sets of the upper longitudinal partition plate are spaced apart within the upper detection box. The multiple sets of the upper transverse partition plate and the multiple sets of the upper longitudinal partition plate are perpendicularly arranged to form multiple first channels. Multiple sets of the lower transverse partition plate and the lower longitudinal partition plate are provided. Multiple sets of the lower transverse partition plate are spaced apart within the lower detection box. Multiple sets of the lower longitudinal partition plate are spaced apart within the lower detection box. The multiple sets of the lower transverse partition plate and the multiple sets of the lower longitudinal partition plate are perpendicularly arranged to form multiple second channels.

[0011] Multiple sets of first channels are respectively arranged directly above multiple sets of second channels, and the first channels and second channels have the same cross-section. The driving mechanism is arranged on the upper detection box and the lower detection box, and is used to lower the upper detection box to clamp the diaphragm in conjunction with the lower detection box, and to make the upper detection box and the lower detection box move horizontally synchronously. The marking component is arranged on the lower transverse partition plate and the lower longitudinal partition plate, and is used to detect the gas flow rate entering the second channel per unit time, and to mark the unqualified areas according to the detection results.

[0012] By adopting the above technical solution, after the drive mechanism drives the upper detection box to rise, the diaphragm is placed between the upper and lower detection boxes. Then, the drive mechanism drives the upper detection box to fall, so that the upper and lower detection boxes press against each other to clamp and seal the diaphragm. Then, gas is introduced into the upper detection box through the air inlet to form a stable air pressure inside the upper detection box. The upper transverse partition plate and the upper longitudinal partition plate form multiple sets of first channels, and the lower transverse partition plate and the lower longitudinal partition plate form multiple sets of second channels. The gas in the upper detection box passes through the diaphragm from the first channel and enters the second channel. The marking component in this application can detect the gas flow rate passing through the diaphragm into the second channel per unit time. If the detected gas flow rate is outside the allowable error range of the specified value, it is considered that the air permeability of the diaphragm in that area is unqualified. The marking component can mark the unqualified area so that the staff can analyze the defective area, find the cause of the defect, and also cut the defective area and adapt the remaining intact part to reduce the waste of diaphragm material.

[0013] Optionally, the driving mechanism includes a first cylinder, a second cylinder, a movable frame, a movable plate, a first guide rail, a second guide rail, and a lifting assembly. The first cylinder is fixedly mounted on the first mounting frame. The movable frame is mounted on the telescopic end of the first cylinder. Two sets of the first guide rail are provided, parallel to the length direction of the first mounting frame, and positioned between the movable frame and the first mounting frame. The movable frame is slidably mounted on the first guide rail. The second cylinder is fixedly mounted on the movable frame. The movable plate is mounted on the telescopic end of the second cylinder and positioned above the movable frame. Two sets of the second guide rail are provided on the side of the movable frame away from the first guide rail. The two sets of the second guide rail are parallel to each other and perpendicular to the first guide rail, positioned between the movable frame and the movable plate. The movable plate is slidably mounted on the second guide rail. The lifting assembly is mounted on the movable plate and the upper detection box, and is used to lift the upper detection box.

[0014] By adopting the above technical solution, when the lifting assembly moves the upper and lower detection boxes to clamp the diaphragm, the contact between the upper and lower transverse partition plates and the upper and lower longitudinal partition plates will create blind spots for testing the air permeability of the diaphragm. Therefore, it is necessary to move the positions of the upper and lower detection boxes to achieve comprehensive testing of the air permeability of the diaphragm. The first cylinder is activated, and its extension and retraction allow for movement of the movable frame in both positive and negative directions along the horizontal X-axis. The second cylinder is activated, and its extension and retraction allow for movement of the movable plate in both positive and negative directions along the Y-axis. This enables the upper and lower detection boxes to move synchronously in both positive and negative directions along the horizontal X-axis and Y-axis. After one clamping detection in the initial state, the movement path of the upper and lower detection boxes in this application is as follows: first, move half the length of the second channel in the positive X-axis direction, then perform clamping detection; then, move half the length of the second channel in the positive Y-axis direction, then perform clamping detection; then, move half the length of the second channel in the negative X-axis direction, then perform clamping detection; finally, move half the length of the second channel in the negative Y-axis direction and return to the initial position. This achieves complete detection of the diaphragm. Furthermore, if a defect is found, the marking assembly performs four detections at different locations, and the markings of the defect locations overlap, which can further determine the defect location, further reduce the size of the diaphragm that needs to be cut, and further reduce the waste of diaphragm material.

[0015] Optionally, the lifting assembly includes a third mounting bracket, a third cylinder, a mounting plate, and a fixing rod. The third mounting bracket is positioned directly above the movable plate. The fixing rod is positioned between the movable plate and the third mounting bracket, with one end fixedly connected to the movable plate and the other end fixedly connected to the third mounting bracket. The mounting plate is fixedly mounted on the side wall of the upper detection box and slidably mounted on the fixing rod. The fixed end of the third cylinder is fixedly mounted on the third mounting bracket, and the telescopic end is fixedly mounted on the mounting plate.

[0016] By adopting the above technical solution, the third cylinder is activated. Since the fixed end of the third cylinder is installed on the third mounting bracket and the telescopic end of the third cylinder is installed on the mounting plate on the side wall of the upper detection box, the telescopic end of the third cylinder can be shortened to drive the upper detection box to rise, thereby realizing the lifting and lowering of the upper detection box.

[0017] Optionally, the marking assembly includes a flow sensor, an electromagnet, a spring, a metal block, and an ink strip. Multiple air outlet channels are arranged directly below the multiple sets of the second channels. Multiple sets of flow sensors are arranged within the multiple sets of air outlet channels. Continuous square frame slots are formed on the lower horizontal and lower vertical partitions surrounding the second channels. The electromagnet is positioned on the inner bottom wall of the square frame slot. The metal block is positioned above the electromagnet. The spring is positioned between the electromagnet and the metal block, with one end connected to the inner bottom wall of the square frame slot and the other end connected to the metal block. A slot is formed at the end of the metal block away from the electromagnet, and the ink strip is positioned within the slot. Two sets of each of the electromagnet, spring, metal block, and ink strip are provided, with the two sets of electromagnets, springs, metal blocks, and ink strips arranged alternately, and the two sets of ink strips are of different colors.

[0018] By adopting the above technical solution, the flow sensor detects the airflow entering the second channel. If the detected flow rate is within the allowable error range of the specified value within a unit time, it indicates that the diaphragm permeability test in that area is qualified; otherwise, it is considered unqualified. When the test is unqualified, the electromagnet corresponding to that area is de-energized, the spring extends, and the ink strip on the metal block rises to contact the diaphragm. When the ink strip contacts the diaphragm, it leaves a square mark on the diaphragm, thus marking the defective area. After marking, the electromagnet is energized to attract the metal block and compress the spring, thereby lowering the ink strip. Multiple sets of electromagnets, springs, metal blocks, and ink strips are provided, and these sets are staggered. The ink strips are different colors, and the problems of the diaphragm can be classified by color according to the detection results of the flow sensor. Different colored ink strips are used to mark the diaphragm with dashed lines, which facilitates targeted analysis of the problems of the diaphragm.

[0019] Optionally, the adjustment assembly includes a first drive motor, a second drive motor, a first drive roller group, and a second drive roller group. The first drive roller group and the second drive roller group are respectively disposed on two sets of second mounting brackets. The first drive motor drives the first drive roller group, and the second drive motor drives the second drive roller group. The tension of the diaphragm can be adjusted by the different rotation speeds of the first drive motor and the second drive motor.

[0020] By adopting the above technical solution, the first drive motor drives the first drive roller group to rotate, and the second drive motor drives the second drive roller group to rotate. Since both the first drive roller group and the second drive roller group apply a certain pressure to the diaphragm, when there is a difference in the rotation speed of the first drive motor and the second drive motor, the tension of the diaphragm can be adjusted through the difference in rotation speed, thereby improving the accuracy of the test, restoring the stress state under real working conditions, making the structure of the air permeability test more practical and authoritative, and at the same time avoiding the influence of uneven airflow path caused by wrinkles or local relaxation on the air permeability test.

[0021] Optionally, a flow equalization plate is provided inside the upper detection box, and the flow equalization plate is positioned directly above the first channel.

[0022] By adopting the above technical solution, the flow equalization plate can reduce the flow rate difference when the gas in the upper detection box enters multiple sets of first channels, thereby reducing the difference in detection results caused by the gas flow rate in the upper detection box.

[0023] Optionally, an adjustable telescopic rod is provided on the outer wall of the upper detection box. The end of the adjustable telescopic rod away from the upper detection box is the telescopic end. An adjusting plate is provided on the telescopic end of the adjustable telescopic rod. The end of the adjusting plate away from the adjustable telescopic rod is inserted into the upper detection box for adjusting the number of the first channels put into use according to the width of the diaphragm.

[0024] By adopting the above technical solution, when the widths of the diaphragms to be tested are inconsistent, the telescopic rod can be activated. By adjusting the extension or retraction of the telescopic rod, the adjustment plate can be moved within the upper testing box. When the adjustment plate is moving, the first channel within the upper testing box can be blocked or opened, thereby adjusting the number of the first channels in use to meet the testing needs of diaphragms of more sizes.

[0025] This application also includes a method for online testing of the air permeability of lithium battery separators, comprising the following steps:

[0026] S1: Start the third cylinder to raise the upper detection box, so that the diaphragm passes through the first drive roller group and the second drive roller group, and passes between the upper detection box and the lower detection box. Then adjust the tension of the diaphragm by adjusting the first drive motor and the second drive motor.

[0027] S2: The upper detection box is lowered by the third cylinder and pressed against the lower detection box to clamp the diaphragm. Gas is introduced into the upper detection box through the air inlet and enters multiple sets of first channels, and then passes through the diaphragm into the second channel.

[0028] S3: If one or more of the multiple flow sensors detect that the gas flow in the second channel does not meet the specified value, the electromagnet is de-energized, the spring extends and the ink strip on the metal block comes into contact with the diaphragm to form a rectangular mark, and then the upper detection box is raised by the third cylinder, and the electromagnet is energized to attract the metal block.

[0029] S4: Using the first and second cylinders, the upper and lower detection boxes are moved sequentially in the positive X-axis direction, positive Y-axis direction, and negative X-axis direction. Each displacement is half the length of the second channel. Each movement repeats the operations of S2 and S3 to form a new rectangular mark.

[0030] S5: Reset the positions of the upper and lower detection boxes, and accurately locate the areas with air permeability defects in the diaphragm by the position of the rectangular imprints and the overlapping area of ​​multiple rectangular imprints.

[0031] In summary, this application includes at least one of the following beneficial technical effects:

[0032] 1. After the drive mechanism raises the upper detection box, the diaphragm is placed between the upper and lower detection boxes. The drive mechanism then lowers the upper detection box, causing it to clamp and seal the diaphragm. Gas is then introduced into the upper detection box through the air inlet to create a stable air pressure. The upper transverse and upper longitudinal partitions form multiple sets of first channels, and the lower transverse and lower longitudinal partitions form multiple sets of second channels. Gas from the upper detection box passes through the diaphragm into the second channels via the first channels. The marking component in this application can measure the gas flow rate through the diaphragm into the second channels per unit time. If the gas flow rate is detected to be outside the allowable error range of the specified value, the diaphragm permeability in that area is considered unqualified. The marking component can mark the unqualified area so that the staff can analyze the defective area, find the cause of the defect, and also cut the defective area and adapt the remaining intact part to reduce the waste of diaphragm material. In addition, during the use of the battery after liquid filling, the temperature rise of the battery will cause the diaphragm to be subjected to a high temperature environment. Therefore, this application can also adjust the temperature of the input gas and test the diaphragm permeability at different temperatures, thereby avoiding the situation where the diaphragm has unqualified permeability due to temperature changes.

[0033] 2. When the lifting assembly moves the upper and lower detection boxes to clamp the diaphragm, the contact between the upper and lower transverse partition plates and the upper and lower longitudinal partition plates will create blind spots for testing the air permeability of the diaphragm. Therefore, it is necessary to move the positions of the upper and lower detection boxes to achieve comprehensive testing of the air permeability of the diaphragm. The first cylinder is activated, and its extension and retraction allow the moving frame to move in the positive and negative directions along the horizontal X-axis. The second cylinder is activated, and its extension and retraction allow the moving plate to move in the positive and negative directions along the Y-axis. This enables the upper and lower detection boxes to move synchronously in the positive and negative directions along both the horizontal X-axis and the Y-axis. After performing one clamping detection in the initial state, the movement path of the upper and lower detection boxes in this application is as follows: first, move half the length of the second channel in the positive direction of the X-axis, then perform clamping detection; then move half the length of the second channel in the positive direction of the Y-axis, then perform clamping detection; then move half the length of the second channel in the negative direction of the X-axis, then perform clamping detection; finally, move half the length of the second channel in the negative direction of the Y-axis and return to the initial position. This achieves complete detection of the diaphragm. Furthermore, if a defect is found, the marking assembly performs four detections at different locations, and the markings of the defect locations overlap, which can further determine the defect location, further reduce the size of the diaphragm that needs to be cut, and further reduce the waste of diaphragm material.

[0034] 3. The flow sensor detects the airflow entering the second channel. If the flow rate is within the allowable error range of the specified value within a unit time, it indicates that the diaphragm permeability test in that area is qualified; otherwise, it is considered unqualified. When the test is unqualified, the electromagnet corresponding to that area is de-energized, the spring extends, and the ink strip on the metal block rises to contact the diaphragm. When the ink strip contacts the diaphragm, it leaves a square mark on the diaphragm, thus marking the defective area. After marking, the electromagnet is energized to attract the metal block and compress the spring, thereby lowering the ink strip. Multiple sets of electromagnets, springs, metal blocks, and ink strips are provided, and these sets are staggered. The ink strips are different colors, and the problems of the diaphragm can be classified by color according to the detection results of the flow sensor. Different colored ink strips are used to mark the diaphragm with dashed lines, which facilitates targeted analysis of the problems of the diaphragm.

[0035] 4. During battery assembly, the separator is usually subjected to mechanical stress generated by winding or lamination. Its microporous structure may change due to relaxation or deformation, resulting in changes in pore size, porosity and distribution. If appropriate tension is not applied during testing, it will affect the accuracy of the air permeability test of the separator. Therefore, in order to improve the accuracy of the test, the adjustment component in this application can adjust the tension of the separator itself, restore the stress state under real working conditions, and make the structure of the air permeability test more practical and authoritative. At the same time, adjusting the tension of the separator also avoids the influence of uneven airflow path caused by wrinkles or local relaxation on the air permeability test.

[0036] 5. When the widths of the diaphragms to be tested are inconsistent, activate the telescopic rod. By adjusting the extension or retraction of the telescopic rod, the adjustment plate can be moved within the upper testing box. When the adjustment plate is moving, the first channel within the upper testing box can be blocked or opened, thereby adjusting the number of first channels in use to meet the testing needs of diaphragms of more sizes. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application;

[0039] Figure 2 yes Figure 1 Partial structural diagram;

[0040] Figure 3 yes Figure 2 A cross-sectional schematic diagram of part of the structure.

[0041] Reference numerals: 1. First mounting bracket; 11. Upper detection box; 12. Lower detection box; 13. Air inlet; 14. Second mounting bracket; 2. Detection device; 21. Upper transverse partition plate; 22. Upper longitudinal partition plate; 23. Lower transverse partition plate; 24. Lower longitudinal partition plate; 25. Drive mechanism; 251. First cylinder; 252. Second cylinder; 253. Moving frame; 254. Moving plate; 255. First guide rail; 256. Second guide rail; 257. Lifting assembly; 2571. Third mounting bracket Frame; 2572, Third cylinder; 2573, Mounting plate; 2574, Fixing rod; 26, Marking assembly; 261, Flow sensor; 262, Electromagnet; 263, Spring; 264, Metal block; 265, Ink strip; 266, Square frame groove; 27, First channel; 28, Second channel; 3, Adjustment assembly; 31, First drive motor; 32, Second drive motor; 33, First drive roller group; 34, Second drive roller group; 4, Flow equalization plate; 5, Adjusting telescopic rod; 51, Adjusting plate. Detailed Implementation

[0042] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0043] This application discloses an online testing device and method for the air permeability of lithium battery separators, referring to... Figure 1 , Figure 2 and Figure 3 An online testing device for the air permeability of lithium battery separators includes a first mounting frame 1, on which an upper testing box 11 and a lower testing box 12 are mounted. The upper testing box 11 is lifted and installed directly above the lower testing box 12. When the upper testing box 11 and the lower testing box 12 are attached, they clamp the separator. An air inlet 13 is provided on the upper testing box 11. Testing devices 2 are provided on the upper testing box 11 and the lower testing box 12. Two sets of second mounting frames 14 are bolted and fixedly installed on the first mounting frame 1. The two sets of second mounting frames 14 are symmetrically installed on both sides of the lower testing box 12. Adjustment components 3 are provided on the second mounting frames 14.

[0044] The diaphragm is placed between the upper detection box 11 and the lower detection box 12, and the upper and lower detection boxes 11 are tightly sealed. Gas is then introduced into the upper detection box 11 through the air inlet 13 to create a stable air pressure inside the upper detection box 11. Under the action of air pressure, the gas will penetrate the diaphragm and enter the lower detection box 12. During this process, the detection device 2 of this application can divert the gas, allowing the gas to penetrate the diaphragm in different areas. The detection device 2 can also determine whether there is a permeability defect in the corresponding area by observing the gas passing through the diaphragm in different areas. If a permeability defect exists, the detection device 2 can mark the defective area so that the staff can analyze the defective area, find the cause of the defect, and also cut the defective area and perform adaptive processing on the remaining intact part to reduce the waste of diaphragm material.

[0045] During battery assembly, the separator is usually subjected to mechanical stress generated by winding or lamination. Its microporous structure may change due to relaxation or deformation, resulting in changes in pore size, porosity and distribution. If appropriate tension is not applied during testing, it will affect the accuracy of the air permeability test of the separator. Therefore, in order to improve the accuracy of the test, the adjustment component 3 in this application can adjust the tension of the separator itself, restoring the stress state under real working conditions, making the structure of the air permeability test more practical and authoritative. At the same time, adjusting the tension of the separator also avoids the influence of uneven airflow path caused by wrinkles or local relaxation on the air permeability test.

[0046] Reference Figure 1 , Figure 2 and Figure 3In order to perform zoned air blowing on the diaphragm through the air inlet 13 and to conduct zoned air permeability testing, and to mark areas with air permeability defects, the detection device 2 in this embodiment includes an upper transverse partition plate 21, an upper longitudinal partition plate 22, a lower transverse partition plate 23, a lower longitudinal partition plate 24, a drive mechanism 25, and a marking assembly 26. Multiple sets of the upper transverse partition plate 21 and the upper longitudinal partition plate 22 are welded and installed. Multiple sets of upper transverse partition plates 21 are welded and installed alternately within the upper detection box 11, and multiple sets of upper longitudinal partition plates 22 are welded and installed alternately within the upper detection box 11. The multiple sets of upper transverse partition plates 21 and the multiple sets of upper longitudinal partition plates 22 are arranged perpendicularly to each other to form multiple sets of first channels 27. The lower transverse partition plate 24... Multiple sets of lower transverse partition plates 23 and lower longitudinal partition plates 24 are welded and installed in the lower detection box 12 at intervals. Multiple sets of lower longitudinal partition plates 24 are welded and installed in the lower detection box 12 at intervals. The multiple sets of lower transverse partition plates 23 and lower longitudinal partition plates 24 are arranged perpendicularly to each other to form multiple sets of second channels 28. Multiple sets of first channels 27 are located directly above the multiple sets of second channels 28, and the cross-sections of the first channels 27 and the second channels 28 are the same. The drive mechanism 25 is installed on the upper detection box 11 and the lower detection box 12. The marking component 26 is installed on the lower transverse partition plates 23 and lower longitudinal partition plates 24. A flow equalization plate 4 is provided in the upper detection box 11, and the flow equalization plate 4 is located directly above the first channel 27.

[0047] After the drive mechanism 25 raises the upper detection box 11, the diaphragm is placed between the upper detection box 11 and the lower detection box 12. Then, the drive mechanism 25 lowers the upper detection box 11, causing the upper detection box 11 and the lower detection box 12 to press against each other and clamp and seal the diaphragm. Then, gas is introduced into the upper detection box 11 through the air inlet 13 to create a stable air pressure inside the upper detection box 11. The upper transverse partition plate 21 and the upper longitudinal partition plate 22 form multiple sets of first channels 27, and the lower transverse partition plate 23 and the lower longitudinal partition plate 24 form multiple sets of second channels 28. The gas in the upper detection box 11 passes through the diaphragm from the first channel 27 and enters the second channel 28. The marking component 26 can detect the gas flow rate entering the second channel 28 through the diaphragm within a unit time. If the gas flow rate is detected to be outside the allowable error range of the specified value, the diaphragm permeability in that area is considered unqualified. The marking component 26 can mark the unqualified area so that the staff can analyze the defective area, find the cause of the defect, and also cut the defective area and perform adaptive processing on the remaining intact part to reduce the waste of diaphragm material. The flow equalization plate 4 can reduce the flow rate difference when the gas in the upper detection box 11 enters multiple sets of first channels 27, thereby reducing the difference in detection results caused by the gas flow rate in the upper detection box 11.

[0048] When the upper detection box 11 and the lower detection box 12 abut against each other to clamp the diaphragm, the abutment between the upper transverse partition plate 21 and the lower transverse partition plate 23, and the upper longitudinal partition plate 22 and the lower longitudinal partition plate 24 will create blind spots for testing the air permeability of the diaphragm. (Refer to...) Figure 1 , Figure 2 and Figure 3 Therefore, the drive mechanism 25 in this embodiment includes a first cylinder 251, a second cylinder 252, a movable frame 253, a movable plate 254, a first guide rail 255, a second guide rail 256, and a lifting assembly 257. The first cylinder 251 is bolted to the first mounting frame 1, and the movable frame 253 is welded to the telescopic end of the first cylinder 251. Two sets of first guide rails 255 are installed, and the two sets of first guide rails 255 are installed parallel to the length direction of the first mounting frame 1 between the movable frame 253 and the first mounting frame 1. The movable frame 253 is slidably mounted on the first guide rail 252. 5. The second cylinder 252 is bolted to the movable frame 253. The movable plate 254 is welded to the telescopic end of the second cylinder 252 and is installed above the movable frame 253. Two sets of second guide rails 256 are installed on the side of the movable frame 253 away from the first guide rail 255. The two sets of second guide rails 256 are parallel to each other and are perpendicular to the first guide rail 255. They are installed between the movable frame 253 and the movable plate 254. The movable plate 254 is slidably installed on the second guide rail 256. The lifting assembly 257 is installed on the movable plate 254 and the upper detection box 11.

[0049] When the lifting assembly 257 moves the upper detection box 11 and the lower detection box 12 to clamp the diaphragm, the contact between the upper transverse partition plate 21 and the lower transverse partition plate 23, and the upper longitudinal partition plate 22 and the lower longitudinal partition plate 24 will create a blind spot for testing the air permeability of the diaphragm. Therefore, it is necessary to move the positions of the upper detection box 11 and the lower detection box 12 to achieve comprehensive testing of the air permeable diaphragm. Activating the first cylinder 251 allows the movable frame 253 to move in the positive and negative directions along the horizontal X-axis. Activating the second cylinder 252 allows the movable plate 254 to move in the positive and negative directions along the Y-axis. This enables the upper detection box 11 and lower detection box 12 to move synchronously in the positive and negative directions along both the horizontal X-axis and the Y-axis. After one clamping detection in the initial state, the movement path of the upper detection box 11 and lower detection box 12 in this application is to first move the length of the second channel 28 in the positive direction along the X-axis. Halfway through the process, a clamping test is performed. Then, the second channel 28 is moved halfway along the positive Y-axis, followed by another clamping test. Next, the second channel 28 is moved halfway along the negative X-axis, followed by another clamping test. Finally, the second channel 28 is moved halfway along the negative Y-axis to return to the initial position. This completes the inspection of the diaphragm. If a defect is found, the marking assembly 26 performs four inspections at different positions. The overlapping marks of the defect locations allow for further determination of the defect location, further reducing the size of the diaphragm that needs to be cut and further reducing the waste of diaphragm material.

[0050] Reference Figure 1 , Figure 2 and Figure 3 In order to achieve the lifting and lowering of the upper detection box 11, the lifting assembly 257 in this embodiment includes a third mounting frame 2571, a third cylinder 2572, a mounting plate 2573, and a fixing rod 2574. The third mounting frame 2571 is fixedly installed above the moving plate 254. The fixing rod 2574 is fixedly installed between the moving plate 254 and the third mounting frame 2571, with one end welded to the moving plate 254 and the other end welded to the third mounting frame 2571. The mounting plate 2573 is welded to the side wall of the upper detection box 11 and slidably installed on the fixing rod 2574. The fixing end of the third cylinder 2572 is bolted to the third mounting frame 2571, and the telescopic end is welded to the mounting plate 2573.

[0051] The third cylinder 2572 is activated. Since the fixed end of the third cylinder 2572 is mounted on the third mounting bracket 2571, and the telescopic end of the third cylinder 2572 is mounted on the mounting plate 2573 on the side wall of the upper detection box 11, the shortening of the telescopic end of the third cylinder 2572 can drive the upper detection box 11 to rise, thereby realizing the lifting and lowering of the upper detection box 11. In this embodiment, there are two third cylinders 2572, and the two third cylinders 2572 are symmetrically installed. Two third cylinders 2572 are a preferred method in this embodiment. In other embodiments, they can be adjusted according to the actual situation. In this embodiment, there are four fixing rods 2574 to improve the stability of the upper detection box 11 when it is lifted and lowered. Four rods are a preferred method in this embodiment. In other embodiments, they can be adjusted according to actual needs.

[0052] To reduce waste of membrane material, refer to Figure 1 , Figure 2 and Figure 3 In this embodiment, the marking component 26 includes a flow sensor 261, an electromagnet 262, a spring 263, a metal block 264, and an ink strip 265. Multiple air outlet channels are opened directly below the multiple sets of second channels 28. Multiple sets of flow sensors 261 are fixedly installed, and each set of flow sensors 261 is fixedly installed within one of the multiple sets of air outlet channels. Continuous square frame grooves 266 are opened on the lower transverse partition plate 23 and lower longitudinal partition plate 24 surrounding the second channels 28. The electromagnet 262 is fixedly installed on the inner bottom wall of the square frame groove 266, and the metal block 264 is movably installed. Above the electromagnet 262, a spring 263 is installed between the electromagnet 262 and the metal block 264, with one end welded to the inner bottom wall of the square frame groove 266 and the other end welded to the metal block 264. A slot is provided at the end of the metal block 264 away from the electromagnet 262, and an ink strip 265 is inserted into the slot. Multiple sets of electromagnets 262, springs 263, metal blocks 264 and ink strips 265 are installed, and the multiple sets of electromagnets 262, springs 263, metal blocks 264 and ink strips 265 are arranged alternately, and the multiple sets of ink strips 265 are different colors.

[0053] The flow sensor 261 detects the airflow entering the second channel 28. If the detected flow rate is within the allowable error range of the specified value within a unit time, it indicates that the diaphragm permeability test in that area is qualified; otherwise, it is considered unqualified. When the test is unqualified, the electromagnet 262 corresponding to that area is de-energized, the spring 263 extends, and the ink strip 265 on the metal block 264 rises to abut against the diaphragm. When the ink strip 265 abuts against the diaphragm, it leaves a square mark on the diaphragm, thereby marking the defective area. After marking, the electromagnet 262 is energized to attract the metal block 264. The compression spring 263 is used to lower the ink strip 265. In this embodiment, two sets of electromagnets 262, springs 263, metal blocks 264, and ink strips 265 are provided. The two sets of electromagnets 262, springs 263, metal blocks 264, and ink strips 265 are arranged alternately, and the two sets of ink strips 265 are different colors. Therefore, based on the detection results of the flow sensor 261, the problem of the diaphragm having too good or too poor air permeability can be classified into two color categories. Thus, the diaphragm is marked with dashed lines using ink strips 265 of different colors, which facilitates targeted analysis of the problems existing in the diaphragm.

[0054] Reference Figure 1 , Figure 2 and Figure 3 In order to reproduce the stress state under real working conditions and make the structure of air permeability testing more practical and authoritative, the adjustment component 3 in this embodiment includes a first drive motor 31, a second drive motor 32, a first drive roller group 33, and a second drive roller group 34. The first drive roller group 33 and the second drive roller group 34 are respectively rotatably mounted on two sets of second mounting brackets 14. The first drive motor 31 drives the first drive roller group 33, and the second drive motor 32 drives the second drive roller group 34.

[0055] The first drive motor 31 drives the first drive roller group 33 to rotate, and the second drive motor 32 drives the second drive roller group 34 to rotate. Since both the first drive roller group 33 and the second drive roller group 34 apply a certain pressure to the diaphragm, when there is a difference in the rotation speed of the first drive motor 31 and the second drive motor 32, the tension of the diaphragm can be adjusted by the difference in rotation speed, thereby improving the accuracy of the test, restoring the stress state under real working conditions, making the structure of the air permeability test more practical and authoritative, while also avoiding the influence of uneven airflow path caused by wrinkles or local relaxation on the air permeability test.

[0056] Reference Figure 2 and Figure 3When the width of the diaphragm to be tested changes, part of the first channel 27 needs to be shielded to meet the testing requirements. Therefore, in this embodiment, an adjusting telescopic rod 5 is bolted to the outer wall of the upper detection box 11. The end of the adjusting telescopic rod 5 away from the upper detection box 11 is the telescopic end. An adjusting plate 51 is welded to the telescopic end of the adjusting telescopic rod 5. The end of the adjusting plate 51 away from the adjusting telescopic rod 5 is inserted into the upper detection box 11.

[0057] When the widths of the diaphragms to be tested are inconsistent, the telescopic rod 5 is activated. The telescopic end of the telescopic rod 5 is extended or shortened, which allows the adjusting plate 51 to move within the upper testing box 11. When the adjusting plate 51 moves, the first channel 27 within the upper testing box 11 can be blocked or opened, thereby adjusting the number of first channels 27 in use to meet the testing needs of diaphragms of more sizes.

[0058] The implementation principle of an online testing device for the air permeability of lithium battery separators according to an embodiment of this application is as follows:

[0059] When it is necessary to test the air permeability of the diaphragm and mark the defective areas, the third cylinder 2572 is activated to raise the upper detection box 11, allowing the diaphragm to pass through the first drive roller group 33 and the second drive roller group 34, and between the upper detection box 11 and the lower detection box 12. The tension of the diaphragm is then adjusted by regulating the first drive motor 31 and the second drive motor 32. The third cylinder 2572 lowers the upper detection box 11 to clamp the diaphragm against the lower detection box 12. Gas is introduced into the upper detection box 11 through the air inlet 13, entering multiple sets of first channels 27, and then passing through the diaphragm into the second channel 28. If one or more of the multiple flow sensors 261 detect that the gas flow rate in the second channel 28 does not meet the specified value, the electromagnet 262 is de-energized, and the spring 263 extends, causing the ink strip 265 on the metal block 264 to abut against the diaphragm to form a rectangular mark.

[0060] When further precise positioning of the defect area is required, the upper detection box 11 and the lower detection box 12 are moved sequentially in the positive X-axis direction, positive Y-axis direction, and negative X-axis direction by the first cylinder 251 and the second cylinder 252. Each displacement is half the length of the second channel 28. Each movement repeats the operations of S2 and S3 to form a new rectangular imprint. The superimposed area of ​​multiple rectangular imprints is the area where the diaphragm has an air permeability defect, thereby achieving precise positioning of the defect area.

[0061] When it is necessary to adjust the tension of the diaphragm, the first drive motor 31 drives the first drive roller group 33 to rotate, and the second drive motor 32 drives the second drive roller group 34 to rotate. Since both the first drive roller group 33 and the second drive roller group 34 apply a certain pressure to clamp the diaphragm, when there is a difference in the rotation speed of the first drive motor 31 and the second drive motor 32, the tension of the diaphragm can be adjusted by the difference in rotation speed, thereby improving the accuracy of detection.

[0062] This application also discloses a method for online testing of the air permeability of lithium battery separators:

[0063] S1: Start the third cylinder 2572 to raise the upper detection box 11, so that the diaphragm passes through the first drive roller group 33 and the second drive roller group 34, and passes between the upper detection box 11 and the lower detection box 12. Then adjust the tension of the diaphragm by adjusting the first drive motor 31 and the second drive motor 32.

[0064] S2: The upper detection box 11 is lowered by the third cylinder 2572 and pressed against the lower detection box 12 to clamp the diaphragm. Gas is introduced into the upper detection box 11 through the air inlet 13 and enters into multiple sets of first channels 27, and then passes through the diaphragm into the second channel 28.

[0065] S3: If one or more of the multiple flow sensors 261 detect that the gas flow in the second channel 28 does not meet the specified value, the electromagnet 262 is de-energized, the spring 263 extends and the ink strip 265 on the metal block 264 abuts against the diaphragm to form a rectangular mark, and then the upper detection box 11 is raised by the third cylinder 2572, and the electromagnet 262 is energized to attract the metal block 264.

[0066] S4: The upper detection box 11 and the lower detection box 12 are moved sequentially in the positive X-axis direction, positive Y-axis direction and negative X-axis direction by the first cylinder 251 and the second cylinder 252. Each displacement is half the length of the second channel 28. Each movement repeats the operations of S2 and S3 to form a new rectangular mark.

[0067] S5: Reset the positions of the upper detection box 11 and the lower detection box 12, and accurately locate the area with air permeability defects in the diaphragm by the position of the rectangular imprint and the superimposed area of ​​multiple rectangular imprints.

[0068] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," "third," and similar words used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "a" or "an," and similar words do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising," "including," and similar words mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects. "Above," "below," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0069] The above are all optional embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for on-line detection of lithium battery separator permeability, which is implemented by using a device for on-line detection of lithium battery separator permeability, the detection device comprising a first mounting frame, an upper detection box and a lower detection box arranged on the first mounting frame, the upper detection box being arranged vertically above the lower detection box, the upper detection box and the lower detection box being capable of clamping the separator when being attached, the upper detection box being provided with an air inlet, the upper detection box and the lower detection box being provided with detection devices for blowing air to the separator through the air inlet, detecting the permeability of the separator in different regions, and marking the regions with defects, the first mounting frame being provided with two groups of second mounting frames, the two groups of second mounting frames being symmetrically arranged on the two sides of the lower detection box, the second mounting frames being provided with adjustment assemblies for adjusting the tension of the separator to be detected and continuously moving the separator to realize uninterrupted permeability detection; the detection device comprising a plurality of upper horizontal partition plates, a plurality of upper vertical partition plates, a plurality of lower horizontal partition plates, a plurality of lower vertical partition plates, a driving mechanism and a marking assembly, the plurality of upper horizontal partition plates being arranged in the upper detection box at intervals, the plurality of upper vertical partition plates being arranged in the upper detection box at intervals, the plurality of upper horizontal partition plates and the plurality of upper vertical partition plates being perpendicular to each other to form a plurality of first channels, the plurality of lower horizontal partition plates being arranged in the lower detection box at intervals, the plurality of lower vertical partition plates being arranged in the lower detection box at intervals, the plurality of lower horizontal partition plates and the plurality of lower vertical partition plates being perpendicular to each other to form a plurality of second channels; the plurality of first channels being arranged vertically above the plurality of second channels, and the cross sections of the first channels and the second channels being the same, the driving mechanism being arranged on the upper detection box and the lower detection box, for lowering the upper detection box, clamping the separator with the lower detection box, and synchronously moving the upper detection box and the lower detection box horizontally, the marking assembly being arranged on the lower horizontal partition plates and the lower vertical partition plates, for detecting the gas flow entering the second channels per unit time, and marking the unqualified regions according to the detection results; The marking assembly comprises a plurality of sets of flow sensors, a plurality of sets of electromagnets, a plurality of sets of springs, a plurality of sets of metal blocks and a plurality of sets of ink strips. A plurality of sets of air outlet channels are arranged directly below a plurality of sets of second channels. A plurality of sets of flow sensors are arranged in the plurality of sets of air outlet channels. A continuous square frame groove is formed in a lower horizontal partition plate and a lower vertical partition plate surrounding the second channels. An electromagnet is arranged on the inner bottom wall of the square frame groove. A metal block is arranged above the electromagnet. A spring is arranged between the electromagnet and the metal block, with one end connected to the inner bottom wall of the square frame groove and the other end connected to the metal block. A clamping groove is formed in the end of the metal block away from the electromagnet. An ink strip is arranged in the clamping groove. The plurality of sets of electromagnets, springs, metal blocks and ink strips are staggered and spaced. The plurality of sets of ink strips are different in color. the detection method comprising the following steps: S1: starting a third cylinder of the driving mechanism to raise the upper detection box, so that the separator passes through a first driving roller group and a second driving roller group of the adjustment assembly, passes between the upper detection box and the lower detection box, and then the tension of the separator is adjusted by adjusting a first driving motor and a second driving motor of the adjustment assembly; S2: lowering the upper detection box by the third cylinder to abut against the lower detection box to clamp the separator, introducing gas into the upper detection box through the air inlet, and then the gas enters the second channels through the separator; S3: if one or more of the plurality of flow sensors detects that the gas flow in the second channels does not meet the specified value, the electromagnet is de-energized, the spring is elongated, the ink strip on the metal block abuts against the separator to form a rectangular mark, the upper detection box is raised by the third cylinder, and the electromagnet is energized to attract the metal block. S4: through the first cylinder and the second cylinder of the driving mechanism, the upper detection box and the lower detection box are sequentially moved in the horizontal X-axis positive direction, the Y-axis positive direction and the X-axis negative direction, and each displacement is half the length of the second channel, and each movement respectively repeats the operations of S2 and S3 to form new rectangular marks; S5: reset the positions of the upper detection box and the lower detection box, and accurately position the area with air permeability defects of the diaphragm through the positions of the rectangular marks and the superimposed areas of the plurality of rectangular marks.

2. The method for on-line detection of the gas permeability of the separator for lithium batteries according to claim 1, characterized in that: The driving mechanism comprises the first cylinder, the second cylinder, a moving frame, a moving plate, first guide rails, second guide rails and a lifting assembly. The first cylinder is fixedly arranged on the first mounting frame. The moving frame is arranged on the telescopic end of the first cylinder. The first guide rails are arranged in two groups. The two groups of first guide rails are arranged between the moving frame and the first mounting frame in parallel to the length direction of the first mounting frame. The moving frame is slidingly arranged on the first guide rails. The second cylinder is fixedly arranged on the moving frame. The moving plate is arranged on the telescopic end of the second cylinder and above the moving frame. The second guide rails are arranged in two groups on the side of the moving frame away from the first guide rails. The two groups of second guide rails are parallel to each other and are arranged between the moving frame and the moving plate in perpendicular to the first guide rails. The moving plate is slidingly arranged on the second guide rails. The lifting assembly is arranged on the moving plate and the upper detection box and is used for lifting the upper detection box.

3. The method for on-line detection of the gas permeability of the separator for lithium batteries according to claim 2, characterized in that: The lifting assembly comprises a third mounting frame, the third cylinder, a mounting plate and a fixed rod. The third mounting frame is arranged directly above the moving plate. The fixed rod is arranged between the moving plate and the third mounting frame and is fixedly connected to the moving plate at one end and to the third mounting frame at the other end. The mounting plate is fixedly arranged on the side wall of the upper detection box and is slidingly arranged on the fixed rod. The fixed end of the third cylinder is fixedly arranged on the third mounting frame and the telescopic end is fixedly arranged on the mounting plate.

4. The method for on-line detection of the gas permeability of the separator for lithium batteries according to claim 1, characterized in that: The adjusting assembly comprises the first driving motor, the second driving motor, the first driving roller group and the second driving roller group. The first driving roller group and the second driving roller group are arranged on the two groups of second mounting frames respectively. The first driving motor drives the first driving roller group. The second driving motor drives the second driving roller group. The rotational speeds of the first driving motor and the second driving motor are different, so that the tension of the diaphragm can be adjusted.

5. The method for on-line detection of the gas permeability of the separator for lithium batteries according to claim 1, characterized in that: A flow equalizing plate is arranged in the upper detection box and directly above the first channel.

6. The method for on-line detection of the gas permeability of the separator for lithium batteries according to claim 1, characterized in that: An adjusting telescopic rod is arranged on the outer wall of the upper detection box. The end of the adjusting telescopic rod away from the upper detection box is a telescopic end. An adjusting plate is arranged on the telescopic end of the adjusting telescopic rod. The end of the adjusting plate away from the adjusting telescopic rod is inserted into the upper detection box and is used for adjusting the number of the first channels in use according to the width of the diaphragm.

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