Online detection equipment for air permeability of lithium battery diaphragm and detection method thereof

Abstract

The invention relates to the technical field of lithium battery diaphragm detection, and particularly discloses lithium battery diaphragm air permeability online detection equipment and a detection method thereof.The lithium battery diaphragm air permeability online detection equipment 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, and detection devices are arranged on the upper detection box and the lower detection box; a first mounting frame is arranged on the upper detection box, a second mounting frame is arranged on the first mounting frame, an adjusting assembly is arranged on the second mounting frame, gas is input into the upper detection box through the gas inlet, and the gas penetrates through the diaphragm to enter the lower detection box. Whether air permeability defects exist in the corresponding areas or not is judged through the air penetrating through the diaphragm in the areas, the detection device marks the areas with the defects, material waste is reduced, the adjusting assembly adjusts the tension of the diaphragm, the stress state under the real working condition is restored, and uneven airflow paths caused by wrinkles or local relaxation are further avoided.

Description

Technical Field

[0001] The present application relates to the technical field of lithium battery diaphragm detection, and in particular to an online detection device and a detection method for the gas permeability of lithium battery diaphragms. Background Art

[0002] The permeability of lithium battery membranes refers to the difficulty of gas or ions passing through the microporous structure of the membrane. It is usually quantified by the Gurley value, which indicates the time required for a certain volume of gas to pass through a unit area of ​​the membrane under a standard pressure difference. Its core function is to balance ion transmission 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 the existing technology, the gas permeability of lithium battery diaphragms is generally tested using a gas pressure differential flow detection device. The core of the device includes a closed test chamber, a precision pressure control system, a gas flow meter and a timing module. The closed test chamber includes upper and lower clamps. During operation, the diaphragm roll is cut into diaphragm samples of appropriate length, and then the diaphragm samples are fixed between the upper and lower clamps. The precision pressure control system maintains a constant pressure difference, and the gas flow and timing module are used to determine the time for the gas to completely penetrate the diaphragm, or the amount of gas penetrating the diaphragm per unit time, to determine whether the permeability of the tested diaphragm is within the error range allowed by the specification value.

[0004] Regarding the above-mentioned related technologies, the upper and lower clamps clamp the entire diaphragm sample for testing. If the air permeability is unqualified, the defective area of ​​the diaphragm sample cannot be found, and the entire diaphragm sample will be wasted. The diaphragm roll needs to be cut into diaphragm samples of appropriate length, and then the diaphragm samples need to be tested one by one, which is more troublesome and cannot realize the testing of diaphragm samples under different tensions. Therefore, improvements are made to this. Summary of the Invention

[0005] In order to achieve uninterrupted detection of diaphragms under different tensions and locate defective areas of the diaphragms, the present application provides an online detection device and a detection method for the air permeability of lithium battery diaphragms.

[0006] This application provides an online detection device for the gas permeability of lithium battery diaphragms, which adopts the following technical solutions: A device for online gas permeability testing of lithium battery diaphragms, comprising a first mounting frame, an upper testing box and a lower testing box being provided on the first mounting frame, the upper testing box being lifted and arranged directly above the lower testing box, the upper testing box and the lower testing box clamping the diaphragm when they are in contact, an air inlet being provided on the upper testing box, the upper testing box and the lower testing box being provided with testing devices for blowing air into the diaphragm in different areas through the air inlet, performing gas permeability testing on the different areas, and marking areas with gas permeability defects, a second mounting frame being provided on the first mounting frame, the second mounting frame being provided with two groups, the two groups of the second mounting frames being symmetrically arranged on both sides of the lower testing box, the second mounting frame being provided with an adjustment component for adjusting the tension of the diaphragm to be tested, and continuously moving the diaphragm to achieve uninterrupted gas permeability testing.

[0007] By adopting the above technical solution, the diaphragm is placed between the upper detection box and the lower detection box, and the upper detection box and the lower detection box are tightly sealed, and then gas is input into the upper detection box through the air inlet to form a stable air pressure in the upper detection box. Under the action of the air pressure, the gas will penetrate the diaphragm and enter the lower detection box. During this process, the detection device in the present application can divert the gas flow so that the gas penetrates the diaphragm in different areas, and can judge whether there is a permeability defect in the corresponding area by the gas passing through the diaphragm in different areas. If there is a permeability defect, the detection device can mark the defective area so that the staff can analyze the defective area and find out the cause of the defect. The defective area can also be cut and the remaining intact part can be adaptively processed to reduce the waste of diaphragm material. In addition, during the use of the battery after liquid filling, the temperature of the battery will increase, causing the diaphragm to experience a high temperature environment. Therefore, the present application can also adjust the temperature of the input gas and detect the permeability of the diaphragm at different temperatures, thereby avoiding the situation where the diaphragm has unqualified permeability due to temperature changes.

[0008] During the battery assembly process, the diaphragm is usually subjected to mechanical stress caused by winding or lamination. Its microporous structure may change the pore size, porosity and distribution due to relaxation or deformation. If appropriate tension is not applied during the test, it will affect the accuracy of the permeability test of the diaphragm. Therefore, in order to improve the accuracy of the test, the adjustment component in this application can adjust the tension of the diaphragm itself, restore the stress state under the actual working conditions, and make the structure of the permeability test more practical and authoritative. At the same time, adjusting the tension of the diaphragm also avoids the influence of uneven airflow path caused by wrinkles or local relaxation on the permeability test.

[0009] 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, the upper transverse partition plates and the upper longitudinal partition plates are each provided with multiple groups, multiple groups of the upper transverse partition plates are spaced apart in the upper detection box, multiple groups of the upper longitudinal partition plates are spaced apart in the upper detection box, multiple groups of the upper transverse and upper longitudinal partition plates are perpendicularly arranged to form multiple groups of first channels, the lower transverse partition plates and the lower longitudinal partition plates are each provided with multiple groups, multiple groups of the lower transverse partition plates are spaced apart in the lower detection box, multiple groups of the lower longitudinal partition plates are spaced apart in the lower detection box, multiple groups of the lower transverse and lower longitudinal partition plates are perpendicularly arranged to form multiple groups of second channels; Multiple groups of the first channels are respectively arranged directly above multiple groups of the second channels, and the cross-sections of the first channels and the second channels are the same. The driving mechanism is arranged on the upper detection box and the lower detection box, and is used to lower the upper detection box, cooperate with the lower detection box to clamp the diaphragm, and make the upper detection box and the lower detection box move horizontally synchronously. The marking component is arranged on the lower horizontal partition plate and the lower longitudinal partition plate, and is used to detect the gas flow entering the second channel per unit time, and mark the unqualified areas according to the detection results.

[0010] By adopting the above technical solution, after the driving mechanism drives the upper detection box to rise, the diaphragm is placed between the upper detection box and the lower detection box, and then the upper detection box is driven down by the driving mechanism, so that the upper detection box and the lower detection box are tightly pressed against each other to clamp and seal the diaphragm, and then gas is input into the upper detection box through the air inlet to form a stable air pressure in the upper detection box. The upper transverse partition plate and the upper longitudinal partition plate are arranged to form multiple groups of first channels, and the lower transverse partition plate and the lower longitudinal partition plate are arranged to form multiple groups of second channels. The gas in the upper detection box passes through the diaphragm from the first channel to the second channel respectively. The marking component in this application can detect the gas flow rate passing through the diaphragm and entering the second channel per unit time. If the gas flow rate is detected to be outside the error range allowed by the specified value, it is deemed that the diaphragm in the area is unqualified. The marking component can mark the unqualified area so that the staff can analyze the defective area and find out the cause of the defect. The defective area can also be cut and the remaining intact part can be adaptively processed to reduce the waste of diaphragm material.

[0011] 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 arranged on the first mounting frame, the movable frame is arranged on the telescopic end of the first cylinder, the first guide rail is provided with two groups, the two groups of first guide rails are parallel to the length direction of the first mounting frame and are arranged between the movable frame and the first mounting frame, the movable frame is slidably arranged on the first guide rail, the second cylinder is fixedly arranged on the movable frame, the movable plate is arranged on the telescopic end of the second cylinder and is arranged above the movable frame, the second guide rail is provided with two groups and is arranged on the side of the movable frame away from the first guide rail, the two groups of second guide rails are parallel to each other and are both perpendicular to the first guide rail and are arranged between the movable frame and the movable plate, the movable plate is slidably arranged on the second guide rail, and the lifting assembly is arranged on the movable plate and the upper detection box for lifting the upper detection box.

[0012] By adopting the above technical solution, when the lifting assembly drives the upper detection box and the lower detection box to abut against and clamp the diaphragm, the abutment between the upper horizontal partition plate and the lower horizontal partition plate, and the upper longitudinal partition plate and the lower longitudinal partition plate will form a blind spot for the permeability test of the diaphragm. Therefore, it is necessary to move the positions of the upper detection box and the lower detection box to achieve comprehensive testing of the breathable diaphragm. Start the first cylinder, and the extension and retraction of the first cylinder can realize the movement of the movable frame in the positive and negative directions of the horizontal X-axis. Start the second cylinder, and the extension end of the second cylinder can realize the movement of the movable plate in the positive and negative directions of the Y-axis, so that the upper detection box and the lower detection box can be synchronously moved in the positive and negative directions of the horizontal X-axis and the positive and negative directions of the Y-axis. After a clamping detection is completed in the initial state, the movement path of the upper detection box and the lower detection box in the present application is to first move half of the second channel length in the positive direction of the X-axis, and then perform a clamping detection, and then move half of the second channel length in the positive direction of the Y-axis, and then perform a clamping detection, and then move half of the second channel length in the negative direction of the X-axis, and then perform a clamping detection, and finally move half of the second channel length in the negative direction of the Y-axis to restore the initial position, so as to realize complete detection of the diaphragm. If there is a defective position, the marking component is detected four times at different positions, and the marks of the defective position overlap, which can further determine the defective position, further reduce the size of the diaphragm to be cut, and further reduce the waste of diaphragm material.

[0013] Optionally, the lifting assembly includes a third mounting bracket, a third cylinder, a mounting plate and a fixed rod, the third mounting bracket is arranged directly above the movable plate, the fixed rod is arranged between the movable plate and the third mounting bracket, and one end is fixedly connected to the movable plate, and the other end is fixedly connected to the third mounting bracket, the mounting plate is fixedly set on the side wall of the upper detection box and slidably set on the fixed rod, the fixed end of the third cylinder is fixedly set on the third mounting bracket, and the telescopic end is fixedly set on the mounting plate.

[0014] By adopting the above technical solution, the third cylinder is started. Since the fixed end of the third cylinder is installed on the third mounting frame, and the telescopic end of the third cylinder is installed on the mounting plate on the side wall of the upper detection box, the shortening of the telescopic end of the third cylinder can drive the upper detection box to rise, thereby realizing the lifting and lowering of the upper detection box.

[0015] Optionally, the marking assembly includes a flow sensor, an electromagnet, a spring, a metal block and an ink stick, and multiple groups of air outlet channels are arranged directly below the multiple groups of second channels. The flow sensors are provided in multiple groups, and the multiple groups of flow sensors are respectively arranged in the multiple groups of air outlet channels. The lower horizontal partition plate and the lower longitudinal partition plate surrounding the second channel are provided with continuous square frame grooves, the electromagnet is arranged on the inner bottom wall of the square frame groove, the metal block is arranged above the electromagnet, the spring is arranged between the electromagnet and the metal block, and one end is connected to the inner bottom wall of the square frame groove and the other end is connected to the metal block. The metal block has a slot at the end away from the electromagnet, and the ink stick is arranged in the slot, and the electromagnet, the spring, the metal block and the ink stick are each provided with two groups, and the two groups of the electromagnets, the springs, the metal blocks and the ink sticks are staggered and spaced, and the colors of the two groups of ink sticks are different.

[0016] By adopting the above technical solution, the flow sensor detects the air flow entering the second channel. If the flow rate detected within a unit time is within the error range allowed by the specified value, it means that the air permeability test of the diaphragm in the area is qualified, otherwise it is deemed unqualified. When the test is unqualified, the electromagnet corresponding to the area is de-energized, and the spring extends to drive the ink strip on the metal block to rise and abut against the diaphragm. When the ink strip abuts against the diaphragm, a square mark is left on the diaphragm, thereby marking the defective area. After the marking is completed, the electromagnet is energized to attract the metal block and compress the spring, thereby lowering the ink strip. There are multiple groups of electromagnets, springs, metal blocks and ink strips, and the multiple groups of electromagnets, springs, metal blocks and ink strips are staggered and spaced apart. The colors of the multiple groups of ink strips are different. According to the detection results of the flow sensor, the problems existing in the diaphragm can be color-graded, so that the diaphragm can be marked with dotted lines using ink strips of different colors, thereby facilitating targeted analysis of the problems existing in the diaphragm.

[0017] Optionally, the adjustment component 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 arranged on two groups of the second mounting frames, the first drive motor drives the first drive roller group, and the second drive motor drives the second drive roller group. The different rotational speeds of the first drive motor and the second drive motor can achieve adjustment of the tension of the diaphragm.

[0018] 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 the first drive roller group and the second drive roller group both clamp the diaphragm with a certain pressure, when there is a difference in the rotational speeds of the first drive motor and the second drive motor, the tension of the diaphragm can be adjusted by the speed difference, 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.

[0019] Optionally, a flow balancing plate is provided in the upper detection box, and the flow balancing plate is provided directly above the first channel.

[0020] By adopting the above technical solution, the flow equalizing plate can reduce the flow velocity difference of the gas in the upper detection box when entering the multiple groups of first channels respectively, thereby reducing the difference in detection results caused by the gas flow velocity in the upper detection box.

[0021] Optionally, an adjustable telescopic rod is provided on the outer wall of the upper detection box, and the end of the adjustable telescopic rod away from the upper detection box is the telescopic end. An adjustment plate is provided on the telescopic end of the adjustable telescopic rod, and the end of the adjustment plate away from the adjustable telescopic rod is socketed and arranged in the upper detection box, for adjusting the number of the first channels put into use according to the width of the diaphragm.

[0022] By adopting the above technical solution, when the width of the diaphragms to be tested is inconsistent, the adjustment telescopic rod is started and the telescopic end of the telescopic rod is adjusted to extend or shorten, so that the adjustment plate can be moved in the upper detection box. When the adjustment plate is moving, the first channel in the upper detection box can be covered or opened, thereby adjusting the number of first channels put into use to meet the detection needs of diaphragms of more sizes.

[0023] The present application also includes a method for online detection of gas permeability of a lithium battery diaphragm, comprising the following steps: 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 through between the upper detection box and the lower detection box, and then adjusts the tension of the diaphragm by adjusting the first drive motor and the second drive motor; S2: The upper detection box is lowered by the third cylinder to press against the lower detection box to clamp the diaphragm. Gas is introduced into the upper detection box through the air inlet and enters the multiple groups of first channels respectively, and then passes through the diaphragm into the second channels; 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 contacts the diaphragm to form a rectangular mark. The upper detection box is then raised by the third cylinder, and the electromagnet is energized to attract the metal block. S4: Using the first cylinder and the second cylinder, the upper detection box and the lower detection box are moved in the horizontal X-axis positive direction, Y-axis positive direction, and X-axis negative direction in sequence, and each displacement is half the length of the second channel. The operations of S2 and S3 are repeated for each movement to form a new rectangular mark. S5: Reset the positions of the upper detection box and the lower detection box, and accurately locate the area of ​​the diaphragm with air permeability defects through the position of the rectangular mark and the overlapping area of ​​multiple rectangular marks.

[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. After the driving mechanism drives the upper detection box to rise, the diaphragm is placed between the upper detection box and the lower detection box, and then the driving mechanism drives the upper detection box to descend, so that the upper detection box and the lower detection box are tightly pressed against the diaphragm to clamp and seal, and then gas is input into the upper detection box through the air inlet to form a stable air pressure in the upper detection box. The upper transverse partition plate and the upper longitudinal partition plate are enclosed into multiple groups of first channels, and the lower transverse partition plate and the lower longitudinal partition plate are enclosed into multiple groups of second channels. The gas in the upper detection box passes through the diaphragm from the first channel and enters the second channel respectively. The marking component in this application can mark the gas flow rate passing through the diaphragm and entering the second channel per unit time. Detection: If the gas flow rate is detected to be outside the error range allowed by the specified value, the permeability of the diaphragm in this area is deemed to be unqualified. The marking component can mark the unqualified area so that the staff can analyze the defective area and find out the cause of the defect. The defective area can also be cut and the remaining intact part can be adaptively processed to reduce the waste of diaphragm materials. In addition, during the use of the battery after liquid filling, the temperature of the battery rises, causing the diaphragm to experience a high temperature environment. Therefore, the present 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; 2. When the lifting assembly drives the upper detection box and the lower detection box to abut against each other to clamp the diaphragm, the abutment between the upper horizontal partition plate and the lower horizontal partition plate, and the upper vertical partition plate and the lower vertical partition plate will form a blind spot for the permeability test of the diaphragm. Therefore, it is necessary to move the positions of the upper detection box and the lower detection box to achieve a comprehensive test of the breathable diaphragm. Start the first cylinder, and the extension and retraction of the first cylinder can realize the movement of the movable frame in the positive and negative directions of the horizontal X-axis. Start the second cylinder, and the extension end of the second cylinder can realize the movement of the movable plate in the positive and negative directions of the Y-axis, so that the upper detection box and the lower detection box can be synchronously moved in the positive and negative directions of the horizontal X-axis and the positive and negative directions of the Y-axis. After a clamping test is performed in the initial state, the movement path of the upper detection box and the lower detection box in the present application is to first move half of the second channel length in the positive direction of the X-axis, and then perform a clamping test, and then move half of the second channel length in the positive direction of the Y-axis, and then perform a clamping test, and then move half of the second channel length in the negative direction of the X-axis, and then perform a clamping test, and finally move half of the second channel length in the negative direction of the Y-axis to restore the initial position, thereby realizing a complete detection of the diaphragm. If there is a defective position, the marking component is detected four times at different positions, and the marks of the defective position overlap, which can further determine the defective position, further reduce the size of the diaphragm to be cut, and further reduce the waste of diaphragm material. 3. The flow sensor detects the air flow entering the second channel. If the flow rate detected within a unit time is within the error range allowed by the specified value, it means that the air permeability test of the diaphragm in this area is qualified, otherwise it is deemed unqualified. When the test is unqualified, the electromagnet corresponding to the area is de-energized, and the spring extends to drive the ink strip on the metal block to rise and abut against the diaphragm. When the ink strip abuts against the diaphragm, a square mark is left on the diaphragm, thereby marking the defective area. After the marking is completed, the electromagnet is energized to attract the metal block and compress the spring, thereby lowering the ink strip. There are multiple groups of electromagnets, springs, metal blocks and ink strips. The multiple groups of electromagnets, springs, metal blocks and ink strips are staggered and spaced apart, and the colors of the multiple groups of ink strips are different. According to the detection results of the flow sensor, the problems existing in the diaphragm can be color-graded, so that the diaphragm can be marked with dotted lines using ink strips of different colors, thereby facilitating targeted analysis of the problems existing in the diaphragm.

[0025] 4. During the battery assembly process, the diaphragm is typically subjected to mechanical stress caused by winding or lamination. Its microporous structure may relax or deform, resulting in changes in pore size, porosity, and distribution. If appropriate tension is not applied during testing, the accuracy of the diaphragm air permeability test will be affected. Therefore, to improve the accuracy of the test, the adjustment component in this application can adjust the tension of the diaphragm itself, restoring the stress state under actual working conditions, making the air permeability test structure more practical and authoritative. At the same time, adjusting the tension of the diaphragm also avoids the impact of uneven airflow path caused by wrinkles or local relaxation on the air permeability test. 5. When the widths of the diaphragms to be tested are inconsistent, start adjusting the telescopic rod and adjust the telescopic end of the telescopic rod to extend or shorten, so that the adjustment plate can be moved in the upper detection box. When the adjustment plate moves, the first channel in the upper detection box can be covered or opened, thereby adjusting the number of first channels put into use to meet the detection needs of diaphragms of more sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application; Figure 2 yes Figure 1 Schematic diagram of part of the structure; Figure 3 yes Figure 2 Schematic cross-section of part of the structure.

[0028] Figure numerals: 1, first mounting frame; 11, upper detection box; 12, lower detection box; 13, air inlet; 14, second mounting frame; 2, detection device; 21, upper transverse partition plate; 22, upper longitudinal partition plate; 23, lower transverse partition plate; 24, lower longitudinal partition plate; 25, driving 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 frame 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 stick; 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 equalizing plate; 5, adjustment telescopic rod; 51, adjustment plate. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-3 This application is described in further detail.

[0030] The present application discloses an on-line detection device and a detection method for the gas permeability of a lithium battery diaphragm. Figure 1 、 Figure 2 and Figure 3 , an online detection device for the air permeability of a lithium battery diaphragm, comprising a first mounting frame 1, on which an upper detection box 11 and a lower detection box 12 are mounted, the upper detection box 11 being lifted and mounted directly above the lower detection box 12, the upper detection box 11 and the lower detection box 12 clamping the diaphragm when they are in contact, an air inlet 13 being opened on the upper detection box 11, and a detection device 2 being provided on the upper detection box 11 and the lower detection box 12, two sets of second mounting frames 14 being fixedly mounted with bolts on the first mounting frame 1, the two sets of second mounting frames 14 being symmetrically mounted on both sides of the lower detection box 12, and an adjustment component 3 being provided on the second mounting frame 14.

[0031] The diaphragm is placed between the upper detection box 11 and the lower detection box 12, and the upper detection box 11 and the lower detection box 12 are tightly sealed, and then gas is input into the upper detection box 11 through the air inlet 13 to form a stable air pressure in the upper detection box 11. Under the action of the air pressure, the gas will penetrate the diaphragm and enter the lower detection box 12. During this process, the detection device 2 in the present application can divert the gas flow so that the gas penetrates the diaphragm in different areas, and can judge whether there is a permeability defect in the corresponding area through the gas passing through the diaphragm in different areas. If there is a permeability defect, the detection device 2 can mark the defective area so that the staff can analyze the defective area and find out the cause of the defect. The defective area can also be cut and the remaining intact part can be adaptively processed to reduce the waste of diaphragm material.

[0032] During the battery assembly process, the diaphragm is usually subjected to mechanical stress caused by winding or lamination. Its microporous structure may change the pore size, porosity and distribution due to relaxation or deformation. If appropriate tension is not applied during the test, it will affect the accuracy of the permeability test of the diaphragm. Therefore, in order to improve the accuracy of the test, the adjustment component 3 in the present application can adjust the tension of the diaphragm itself, restore the stress state under the actual working conditions, and make the structure of the permeability test more practical and authoritative. At the same time, adjusting the tension of the diaphragm also avoids the influence of uneven airflow path caused by wrinkles or local relaxation on the permeability test.

[0033] Reference Figure 1 、 Figure 2 and Figure 3In order to blow air into the diaphragm in different areas through the air inlet 13, perform air permeability detection in different areas, and 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 driving mechanism 25 and a marking assembly 26. The upper transverse partition plates 21 and the upper longitudinal partition plates 22 are welded and installed in multiple groups. The multiple groups of upper transverse partition plates 21 are welded and installed in the upper detection box 11 at intervals. The multiple groups of upper longitudinal partition plates 22 are welded and installed in the upper detection box 11 at intervals. The multiple groups of upper transverse and upper longitudinal partition plates 22 are perpendicular to each other and enclose multiple groups of first channels 27. The lower transverse partition plates 2 3 and the lower longitudinal partition plates 24 are welded and installed in multiple groups, multiple groups of lower transverse partition plates 23 are welded and installed at intervals in the lower detection box 12, multiple groups of lower longitudinal partition plates 24 are welded and installed at intervals in the lower detection box 12, multiple groups of lower transverse and multiple groups of lower longitudinal partition plates 24 are perpendicular to each other and enclose multiple groups of second channels 28; multiple groups of first channels 27 are respectively located directly above the multiple groups of second channels 28, and the cross-sections of the first channels 27 and the second channels 28 are the same, the driving mechanism 25 is installed on the upper detection box 11 and the lower detection box 12, the marking assembly 26 is installed on the lower transverse partition plate 23 and the lower longitudinal partition plate 24, and a flow equalizing plate 4 is provided in the upper detection box 11, and the flow equalizing plate 4 is provided directly above the first channel 27.

[0034] After the driving mechanism 25 drives the upper detection box 11 to rise, the diaphragm is placed between the upper detection box 11 and the lower detection box 12, and then the driving mechanism 25 drives the upper detection box 11 to descend, so that the upper detection box 11 and the lower detection box 12 are tightly pressed against the diaphragm to clamp and seal, and then gas is input into the upper detection box 11 through the air inlet 13 to form a stable air pressure in the upper detection box 11. The upper transverse partition plate 21 and the upper longitudinal partition plate 22 are enclosed into multiple groups of first channels 27, and the lower transverse partition plate 23 and the lower longitudinal partition plate 24 are enclosed into multiple groups 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 passing through the diaphragm and entering the second channel 28 per unit time. If the gas flow rate is detected to be outside the error range allowed by the specified value, it is deemed that the air permeability of the diaphragm in this area is unqualified. The marking component 26 can mark the unqualified area so that the staff can analyze the defective area and find out the cause of the defect. The defective area can also be trimmed and the remaining intact part can be adaptively processed to reduce the waste of diaphragm material. The flow equalizing plate 4 can reduce the flow rate difference of the gas in the upper detection box 11 when entering the multiple groups of first channels 27 respectively, thereby reducing the difference in detection results caused by the gas flow rate in the upper detection box 11.

[0035] 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 form a blind spot for the permeability test of the diaphragm. Figure 1 、 Figure 2 and Figure 3 Therefore, the driving 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 fixedly mounted on the first mounting frame 1 with bolts, and the movable frame 253 is welded to the telescopic end of the first cylinder 251. Two groups of first guide rails 255 are installed. The two groups of first guide rails 255 are parallel to the length direction of the first mounting frame 1 and are installed between the movable frame 253 and the first mounting frame 1. The movable frame 253 is slidably mounted on the first guide rails 255. 5, the second cylinder 252 is fixedly mounted on the mobile frame 253 by bolts, the mobile plate 254 is welded to the telescopic end of the second cylinder 252, and is installed above the mobile frame 253, two sets of second guide rails 256 are installed and are installed on the side of the mobile frame 253 away from the first guide rail 255, the two sets of second guide rails 256 are parallel to each other and are both perpendicular to the first guide rail 255 and are installed between the mobile frame 253 and the mobile plate 254, the mobile plate 254 is slidably mounted on the second guide rails 256, and the lifting assembly 257 is installed on the mobile plate 254 and the upper detection box 11.

[0036] When the lifting assembly 257 drives the upper detection box 11 and the lower detection box 12 to abut against each other to clamp the diaphragm, the abutment between the upper horizontal partition plate 21 and the lower horizontal partition plate 23, and the upper longitudinal partition plate 22 and the lower longitudinal partition plate 24 will form a blind spot for the permeability test 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 breathable diaphragm. Start the first cylinder 251, and the extension and retraction of the first cylinder 251 can realize the movement of the movable frame 253 in the positive and negative directions on the horizontal X-axis. Start the second cylinder 252, and the extension end of the second cylinder 252 can realize the movement of the movable plate 254 in the positive and negative directions on the Y-axis, so as to realize the synchronous movement of the upper detection box 11 and the lower detection box 12 in the positive and negative directions on the horizontal X-axis and the positive and negative directions on the Y-axis. After a clamping test is completed in the initial state, the movement path of the upper detection box 11 and the lower detection box 12 in the present application is to first move in the positive direction of the X-axis by the length of the second channel 28. The diaphragm is completely inspected by moving the marking component 26 in the positive direction of the Y axis by half of the length of the second channel 28, and then the clamping inspection is performed. The diaphragm is then moved in the negative direction of the X axis by half of the length of the second channel 28, and then the clamping inspection is performed. The diaphragm is finally restored to its initial position by moving the marking component 26 in the negative direction of the Y axis by half of the length of the second channel 28 to restore its initial position. In this way, the diaphragm is completely inspected. If there is a defective position, the marking component 26 is inspected in four different positions, and the marks of the defective position overlap, so as to further determine the defective position, further reduce the size of the diaphragm to be cut, and further reduce the waste of diaphragm material.

[0037] 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 fixed rod 2574. The third mounting frame 2571 is fixedly installed directly above the movable plate 254. The fixed rod 2574 is fixedly installed between the movable plate 254 and the third mounting frame 2571, and one end is welded to the movable plate 254, and the other end is welded to the third mounting frame 2571. The mounting plate 2573 is welded to the side wall of the upper detection box 11 and is slidably installed on the fixed rod 2574. The fixed end of the third cylinder 2572 is fixedly installed on the third mounting frame 2571 with a bolt, and the telescopic end is welded and fixed to the mounting plate 2573.

[0038] Start the third cylinder 2572. 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, the number of third cylinders 2572 is two, and the two third cylinders 2572 are symmetrically installed. The two third cylinders 2572 are a preferred method of this embodiment, and can be adjusted according to actual conditions in other embodiments. In this embodiment, the number of fixed rods 2574 is four, which are used to improve the stability of the upper detection box 11 during lifting and lowering. Four is a preferred method of this embodiment, and can be adjusted according to actual needs in other embodiments.

[0039] In order to reduce the waste of diaphragm materials, refer to Figure 1 、 Figure 2 and Figure 3 The marking assembly 26 in this embodiment includes a flow sensor 261, an electromagnet 262, a spring 263, a metal block 264 and an ink stick 265. A plurality of air outlet channels are provided directly below the plurality of second channels 28. The flow sensors 261 are fixedly installed in the plurality of channels. The plurality of flow sensors 261 are respectively fixedly installed in the plurality of air outlet channels. A continuous square frame groove 266 is provided on the lower horizontal partition plate 23 and the lower vertical 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. 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, and one end is welded to the inner bottom wall of the square frame groove 266, and the other end is welded to the metal block 264. A slot begins to form at the end of the metal block 264 away from the electromagnet 262, and the ink strip 265 is placed in the slot. The electromagnet 262, spring 263, metal block 264 and ink strip 265 are installed in multiple groups, and the multiple groups of electromagnets 262, springs 263, metal blocks 264 and ink strips 265 are staggered and spaced apart, and the colors of the multiple groups of ink strips 265 are different.

[0040] The flow sensor 261 detects the air flow entering the second channel 28. If the flow rate detected per unit time is within the error range allowed by the specified value, it means that the air permeability test of the diaphragm in the area is qualified. Otherwise, it is considered unqualified. When the test fails, the electromagnet 262 corresponding to the area is powered off, and the spring 263 extends to drive the ink strip 265 on the metal block 264 to rise and abut against the diaphragm. When the ink strip 265 abuts against the diaphragm, a square mark is left on the diaphragm, thereby marking the defective area. After the marking is completed, the electromagnet 262 is energized to attract the metal block 264. The compression spring 263 is used to achieve the descent of the ink strip 265. In the present embodiment, two groups of electromagnets 262, springs 263, metal blocks 264 and ink strips 265 are provided. The two groups of electromagnets 262, springs 263, metal blocks 264 and ink strips 265 are arranged at staggered intervals, and the colors of the two groups of ink strips 265 are different. Therefore, according to the detection results of the flow sensor 261, the problems of too good and too poor air permeability of the diaphragm can be graded into two colors, and the diaphragm can be marked with dotted lines using ink strips 265 of different colors, so as to facilitate targeted analysis of the problems existing in the diaphragm.

[0041] Reference Figure 1 、 Figure 2 and Figure 3 In order to restore the stress state under real working conditions and make the structure of air permeability detection 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 rotatably mounted on two sets of second mounting frames 14 respectively. 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.

[0042] 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 the first drive roller group 33 and the second drive roller group 34 both clamp the diaphragm with a certain pressure, when there is a difference in the rotational speeds of the first drive motor 31 and the second drive motor 32, the tension of the diaphragm can be adjusted by the speed difference, thereby improving the accuracy of the test and restoring the stress state under real working conditions. This makes 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.

[0043] Reference Figure 2 and Figure 3When the width of the diaphragm to be detected changes, part of the first channel 27 needs to be shielded to meet the detection requirements. Therefore, in this embodiment, an adjustable telescopic rod 5 is fixedly installed on the outer wall of the upper detection box 11 by bolts. The end of the adjustable telescopic rod 5 away from the upper detection box 11 is the telescopic end. An adjusting plate 51 is welded and installed on the telescopic end of the adjustable telescopic rod 5. The end of the adjusting plate 51 away from the adjusting telescopic rod 5 is socket-mounted in the upper detection box 11.

[0044] When the widths of the diaphragms to be tested are inconsistent, the adjustment telescopic rod 5 is started and the telescopic end of the telescopic rod 5 is extended or shortened, so that the adjustment plate 51 can be moved in the upper detection box 11. When the adjustment plate 51 moves, the first channel 27 in the upper detection box 11 can be covered or opened, thereby adjusting the number of first channels 27 put into use to meet the detection needs of diaphragms of more sizes.

[0045] The implementation principle of an online detection device for gas permeability of lithium battery diaphragms in the embodiment of the present application is as follows: When the diaphragm needs to be tested for air permeability and defective areas need to be marked, the third air cylinder 2572 is activated to raise the upper test box 11, allowing the diaphragm to pass through the first drive roller assembly 33 and the second drive roller assembly 34, and between the upper test box 11 and the lower test box 12. The tension of the diaphragm is then adjusted by adjusting the first drive motor 31 and the second drive motor 32. The third air cylinder 2572 lowers the upper test box 11 and presses it against the lower test box 12, thereby clamping the diaphragm. Gas is introduced into the upper test box 11 through the air inlet 13, entering the 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 in the second channel 28 does not meet the specified value, the electromagnet 262 is de-energized, and the spring 263 is extended, causing the ink strip 265 on the metal block 264 to contact the diaphragm, forming a rectangular mark.

[0046] When it is necessary to further accurately locate the defective area, the upper detection box 11 and the lower detection box 12 are moved in the horizontal X-axis positive direction, Y-axis positive direction and X-axis negative direction in turn through the first cylinder 251 and the second cylinder 252, and each displacement is half the length of the second channel 28, and the operations of S2 and S3 are repeated for each movement to form new rectangular marks respectively. The overlapping area of ​​multiple rectangular marks is the area where the diaphragm has air permeability defects, thereby achieving accurate positioning of the defective area.

[0047] When the tension of the diaphragm needs to be adjusted, 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 the first drive roller group 33 and the second drive roller group 34 both clamp the diaphragm with a certain pressure, when there is a difference in the rotational speed of the first drive motor 31 and the second drive motor 32, the tension of the diaphragm can be adjusted by the speed difference, thereby improving the accuracy of detection.

[0048] This application also discloses a method for online detection of gas permeability of lithium battery diaphragms: 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, and then adjust the tension of the diaphragm by adjusting the first drive motor 31 and the second drive motor 32; S2: The third cylinder 2572 lowers the upper detection box 11 and presses it 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 the multiple groups of first channels 27, and then passes through the diaphragm into the second channels 28. 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. 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. S4: The upper detection box 11 and the lower detection box 12 are moved in the horizontal X-axis positive direction, Y-axis positive direction, and X-axis negative direction in sequence by the first cylinder 251 and the second cylinder 252, and each displacement is half the length of the second channel 28. The operations of S2 and S3 are repeated for each movement to form a new rectangular mark. S5: Reset the positions of the upper detection box 11 and the lower detection box 12, and accurately locate the area of ​​the membrane with air permeability defects through the position of the rectangular mark and the overlapping area of ​​multiple rectangular marks.

[0049] Unless otherwise defined, the technical or scientific terms used in this application shall have the usual meanings understood by persons of ordinary skill in the field to which this application belongs. The words “first”, “second”, “third” and similar terms used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as “a” or “an” and the like do not indicate a quantity limitation, but rather indicate the existence of at least one. Words such as “include” or “comprise” and the like mean that the elements or objects appearing before “include” or “comprises” cover the elements or objects listed after “include” or “comprises” and their equivalents, and do not exclude other elements or objects. “Up”, “down”, “left”, “right” and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0050] The above are all optional embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. An online detection device for gas permeability of lithium battery diaphragms, characterized by: The invention comprises a first mounting frame (1), wherein an upper detection box (11) and a lower detection box (12) are arranged on the first mounting frame (1), wherein the upper detection box (11) is lifted and arranged directly above the lower detection box (12), and when the upper detection box (11) and the lower detection box (12) are attached, the diaphragm is clamped, an air inlet (13) is provided on the upper detection box (11), and the upper detection box (11) and the lower detection box (12) are provided with air blowing means for blowing air into the diaphragm in different areas through the air inlet (13), and A detection device (2) for performing regional air permeability detection and marking areas with air permeability defects, wherein a second mounting frame (14) is provided on the first mounting frame (1), two groups of the second mounting frames (14) are provided, and the two groups of the second mounting frames (14) are symmetrically arranged on both sides of the lower detection box (12), and an adjustment component (3) is provided on the second mounting frame (14) for adjusting the tension of a diaphragm to be detected and continuously moving the diaphragm to achieve uninterrupted air permeability detection.

2. The on-line gas permeability detection device for lithium battery diaphragms according to claim 1, characterized in that: The detection device (2) comprises 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 driving mechanism (25) and a marking assembly (26), wherein the upper transverse partition plate (21) and the upper longitudinal partition plate (22) are provided in multiple groups, and the multiple groups of the upper transverse partition plates (21) are arranged at intervals in the upper detection box (11), and the multiple groups of the upper longitudinal partition plates (22) are arranged at intervals in the upper detection box (11). The upper transverse and multiple groups of the upper longitudinal partition plates (22) are mutually perpendicularly arranged to form multiple groups of first channels (27), multiple groups of the lower transverse partition plates (23) and the lower longitudinal partition plates (24) are each provided, multiple groups of the lower transverse partition plates (23) are spaced apart in the lower detection box (12), multiple groups of the lower longitudinal partition plates (24) are spaced apart in the lower detection box (12), and multiple groups of the lower transverse and multiple groups of the lower longitudinal partition plates (24) are mutually perpendicularly arranged to form multiple groups of second channels (28); A plurality of groups of the first channels (27) are respectively arranged directly above a plurality of groups of the second channels (28), and the cross sections of the first channels (27) and the second channels (28) are the same. The driving mechanism (25) is arranged on the upper detection box (11) and the lower detection box (12), and is used to lower the upper detection box (11), cooperate with the lower detection box (12) to clamp the diaphragm, and make the upper detection box (11) and the lower detection box (12) move horizontally synchronously. The marking component (26) is arranged on the lower transverse partition plate (23) and the lower longitudinal partition plate (24), and is used to detect the gas flow entering the second channel (28) per unit time, and mark the unqualified area according to the detection result.

3. The on-line gas permeability detection device for lithium battery diaphragms according to claim 2, characterized in that: The driving mechanism (25) comprises 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), wherein the first cylinder (251) is fixedly arranged on the first mounting frame (1), the movable frame (253) is arranged on the telescopic end of the first cylinder (251), two groups of the first guide rails (255) are provided, and the two groups of the first guide rails (255) are arranged between the movable frame (253) and the first mounting frame (1) in parallel with the length direction of the first mounting frame (1), the movable frame (253) is slidably arranged on the first guide rail (255), and the second cylinder (252) is fixedly arranged on the first guide rail (255). The movable plate (254) is arranged on the telescopic end of the second cylinder (252) and is arranged above the movable frame (253). Two groups of second guide rails (256) are provided and are arranged on a surface of the movable frame (253) away from the first guide rail (255). The two groups of second guide rails (256) are parallel to each other and are perpendicular to the first guide rail (255). The movable plate (254) is slidably arranged on the second guide rail (256). The lifting component (257) is provided on the movable plate (254) and the upper detection box (11) for lifting and lowering the upper detection box (11).

4. The on-line gas permeability detection device for lithium battery diaphragms according to claim 3, characterized in that: The lifting assembly (257) includes a third mounting frame (2571), a third cylinder (2572), a mounting plate (2573) and a fixed rod (2574). The third mounting frame (2571) is arranged directly above the movable plate (254). The fixed rod (2574) is arranged between the movable plate (254) and the third mounting frame (2571), and one end is fixedly connected to the movable plate (254), and the other end is fixedly connected to the third mounting frame (2571). The mounting plate (2573) is fixedly arranged on the side wall of the upper detection box (11) and is slidably arranged on the fixed rod (2574). The fixed end of the third cylinder (2572) is fixedly arranged on the third mounting frame (2571), and the telescopic end is fixedly arranged on the mounting plate (2573).

5. The on-line gas permeability detection device for lithium battery diaphragms according to claim 2, characterized in that: The marking assembly (26) includes a flow sensor (261), an electromagnet (262), a spring (263), a metal block (264) and an ink stick (265). A plurality of air outlet channels are provided directly below the plurality of second channels (28). The flow sensor (261) is provided in a plurality of groups. The plurality of flow sensors (261) are respectively provided in the plurality of air outlet channels. A continuous square frame groove (266) is provided on the lower transverse partition plate (23) and the lower longitudinal partition plate (24) surrounding the second channel (28). The electromagnet (262) is provided on the inner bottom wall of the square frame groove (266). The metal block (264) is provided above the electromagnet (262). The spring (263) is arranged between the electromagnet (262) and the metal block (264), and one end is connected to the inner bottom wall of the square frame groove (266), and the other end is connected to the metal block (264). The metal block (264) has a card slot at the end away from the electromagnet (262), and the ink strip (265) is arranged in the card slot. The electromagnet (262), the spring (263), the metal block (264) and the ink strip (265) are all provided in multiple groups. The multiple groups of the electromagnet (262), the spring (263), the metal block (264) and the ink strip (265) are all staggered and spaced, and the colors of the multiple groups of the ink strips (265) are different.

6. The method for online detection of gas permeability of lithium battery diaphragms according to claim 1, characterized in that: The adjustment component (3) 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 arranged on two groups of the second mounting frames (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). The different rotation speeds of the first drive motor (31) and the second drive motor (32) can achieve adjustment of the tension of the diaphragm.

7. The on-line gas permeability detection device for lithium battery diaphragms according to claim 2, characterized in that: A flow balancing plate (4) is provided in the upper detection box (11), and the flow balancing plate (4) is arranged directly above the first channel (27).

8. The on-line gas permeability detection device for lithium battery diaphragms according to claim 2, characterized in that: An adjusting telescopic rod (5) is provided on the outer wall of the upper detection box (11), and the end of the adjusting telescopic rod (5) away from the upper detection box (11) is a telescopic end. An adjusting plate (51) is provided on the telescopic end of the adjusting telescopic rod (5), and the end of the adjusting plate (51) away from the adjusting telescopic rod (5) is socket-inserted in the upper detection box (11) for adjusting the number of the first channels (27) put into use according to the width of the diaphragm.

9. A method for online detection of gas permeability of a lithium battery separator, according to an online detection device for gas permeability of a lithium battery separator according to any one of claims 1 to 8, characterized in that: The following steps are involved: 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), and then adjust the tension of the diaphragm by adjusting the first drive motor (31) and the second drive motor (32); S2: The upper detection box (11) is lowered by the third cylinder (2572) to abut against the lower detection box (12) to clamp the diaphragm, and gas is introduced into the upper detection box (11) through the air inlet (13) and enters the plurality of first channels (27) and then enters the second channels (28) through the diaphragm; S3: If one or more of the plurality of 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) is extended so that the ink strip (265) on the metal block (264) contacts 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 adsorb the metal block (264); S4: The upper detection box (11) and the lower detection box (12) are moved in the positive direction of the horizontal X axis, the positive direction of the Y axis, and the negative direction of the X axis in sequence by the first cylinder (251) and the second cylinder (252), and each displacement is half the length of the second channel (28), and each movement repeats the operations of S2 and S3 to form a new rectangular mark respectively; S5: Resetting the positions of the upper detection box (11) and the lower detection box (12), and accurately locating the area of ​​the membrane with air permeability defects through the position of the rectangular imprint and the overlapping area of ​​multiple rectangular imprints.

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