Device and method for automatically detecting performance of lithium ion battery diaphragm

Abstract

The invention discloses a lithium ion battery diaphragm performance automatic detection device and a detection method thereof.The detection device comprises a feeding mechanism and a detection module, and the detection module comprises a thickness detection unit, a gram weight detection unit, a porosity detection unit, a puncture strength detection unit and an air permeability detection unit; the thickness detection unit adopts a thickness gauge to detect the thickness of the diaphragm; the gram weight detection unit calculates the weight of the diaphragm in unit area according to the measured weight and area; the porosity detection unit calculates the porosity by combining the area and the thickness of the diaphragm; the puncture strength detection unit adopts a needle head to penetrate through the diaphragm, captures the maximum load at the penetration moment, and divides the maximum load by the average thickness of the diaphragm to obtain the puncture strength; the air permeability detection unit evaluates the air permeability by using the time required for the air to pass through the diaphragm with the specific area. According to the invention, comprehensive automatic detection of diaphragm performance can be realized, manual intervention is reduced, detection efficiency is improved, and data of transverse consistency and longitudinal consistency can be well seen.

Description

Technical Field

[0001] The invention relates to an automatic detection device and a detection method for lithium ion battery diaphragm performance, belonging to the technical field of lithium ion battery diaphragm detection. Background Art

[0002] As an important device for modern energy storage, the performance of lithium-ion batteries is directly affected by the quality of the diaphragm. As a key component of the battery, the diaphragm must have appropriate thickness, weight, porosity, air permeability, puncture strength and other characteristics to ensure the safety and efficiency of the battery. At present, most of the diaphragm performance testing devices on the market are manual or semi-automatic, with low detection efficiency and easily affected by human factors, which is difficult to meet the needs of large-scale production lines. Therefore, it is particularly important to develop an automated, efficient and accurate lithium-ion battery diaphragm performance testing device. Summary of the invention

[0003] The purpose of the present invention is to provide an automatic detection device and a detection method for the performance of lithium-ion battery separators. The device can automatically complete the detection of thickness, gram weight, porosity, air permeability and puncture strength after winding, thereby improving the detection efficiency and accuracy and ensuring the quality of battery production.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] On the one hand, the present invention provides an automatic detection device for the performance of lithium-ion battery diaphragms, comprising a feeding mechanism and a detection module, wherein the feeding mechanism is used to feed the cut diaphragms into the detection module; the detection module comprises a thickness detection unit, a gram weight detection unit, a porosity detection unit, a puncture strength detection unit and an air permeability detection unit, and each of the detection units is respectively fixedly mounted on a gantry structure that is relatively arranged up and down.

[0006] Furthermore, the feeding mechanism is located at the starting end of the frame, and includes a reeling device and a conveying device; the reeling device includes a mother roll roller, a guide roller, a meter counter and a cutter. The diaphragm passes from the mother roll roller through the guide roller and the unwinding length is measured by the meter counter. When the reeling reaches a certain number of meters, the cutter automatically starts to cut the diaphragm.

[0007] Furthermore, the conveying device is arranged on both sides of the frame, and includes a chain disk, a driving motor of the chain disk, a clamp arranged on the chain disk, a mechanical clamp closer and a slide rail. The clamps are distributed at both ends of the diaphragm along the length direction of the chain disk. The mechanical clamp closer is used to control the opening and closing of the clamps. The chain disks on both sides are manually adjusted by buttons to move closer or farther away from each other on the slide rail according to the width of the diaphragm. After that, the cut diaphragm is translated into the detection module through the chain disk for detection.

[0008] Furthermore, the thickness detection unit uses a thickness gauge to detect the thickness of the diaphragm; the thickness gauge is slidably installed on the gantry through a guide rail, the upper part of the thickness gauge is installed on the upper gantry, and the lower part of the thickness gauge is installed at a relative position of the lower gantry. The thickness gauge reciprocates in the width direction of the diaphragm through the guide rail, and its measurement results are fed back to the central control computer.

[0009] Furthermore, the gram weight detection unit includes a weighing sensor and an area measuring device, and the weight of the diaphragm per unit area is calculated by the measured weight and area; the area measuring device is composed of a meter counter and an infrared width measuring instrument, the meter counter calculates the number of unwinding meters by the number of unwinding turns, and the infrared width measuring instrument detects the width of the diaphragm by infrared rays, and the area of ​​the membrane is obtained by multiplying the length by the width, and its measurement result is fed back to the central control computer; the weighing sensor is located at the final end of the device, and a support platform and a mechanical arm are provided above the weighing sensor. The support platform is L-shaped, and includes a horizontal platform and a vertical baffle. The baffle is located at the rear end of the platform, and is used to block the diaphragm transported here and stack it on the platform. The mechanical arm is used to clamp the accumulated diaphragm and send it to the weighing sensor for weighing, and the weight after weighing is fed back to the central control computer.

[0010] Furthermore, the porosity detection unit combines the gram weight and thickness of the diaphragm to calculate the porosity according to porosity = (pure PE density - gram weight of diaphragm per unit area / average thickness of diaphragm) / pure PE density * 100%, and the measured value is fed back to the central control computer.

[0011] Furthermore, the puncture strength detection unit includes a puncture base and a needle that are relatively arranged. The diaphragm passes through between the puncture base and the needle. The needle penetrates the diaphragm at a standard speed, and a dynamometer is provided on the needle to capture the maximum load at the moment of penetration. The maximum load is divided by the average thickness of the diaphragm to obtain the puncture strength. The measured value is fed back to the central control computer. The needle is installed on the upper gantry through the dynamometer and can move along the length direction of the upper gantry. The base can maintain the same direction movement as the needle end.

[0012] Furthermore, the air permeability detection unit uses the time required for air to pass through a membrane of a specific area to evaluate the air permeability; the air permeability detection unit includes two gaskets arranged opposite to each other, the center of the gasket is provided with an air vent allowing gas to flow through, the gasket is internally connected to an air pipe for conveying air, and the pressure difference before and after conveying is calculated to convert the amount of gas passing through in a fixed time; the two gaskets arranged opposite to each other in the air permeability detection unit are respectively arranged on the upper and lower gantries, and can make relative movement along the length direction of the gantry.

[0013] On the other hand, the present invention also provides a method for detecting the performance of a lithium-ion battery separator, which comprises the following steps: Step 1, after the main line is wound up, the parent roll is transferred to the front of the guide roll;

[0014] Step 2, delivering the joint of the diaphragm to the clamp of the conveying device, and adjusting the width of the chain disk along the vertical direction of the diaphragm according to the width of the diaphragm, and then closing the clamp;

[0015] Step 3: The chain disk runs at a certain speed. During the operation, the diaphragm is continuously clamped. When the unwinding length reaches the set value, the unwinding roller and the chain disk stop. At this time, the cutter starts automatically and cuts along the vertical direction of the diaphragm to cut the diaphragm.

[0016] Step 4, start the infrared width measuring instrument to measure the diaphragm width;

[0017] Step 5, start the thickness gauge to measure the thickness;

[0018] Step 6, starting the air permeability detection unit to measure the air permeability value of the diaphragm;

[0019] Step 7, starting the puncture strength detection unit, the needle runs through the septum at a standard speed, and the septum puncture strength is measured;

[0020] Step 8: After the measurement is completed, the chain disc starts, the clamp gradually opens, and the diaphragm is accumulated on the support table;

[0021] Step 9: After all the clamps are opened, the mechanical arm starts, grabs the middle position of the diaphragm and sends it to the weighing hopper for weighing;

[0022] Step 10, the central control computer summarizes the data to obtain the thickness, weight, porosity, puncture strength and air permeability of the diaphragm.

[0023] Furthermore, during the measurement process, if the longitudinal consistency of thickness and air permeability needs to be measured, the thickness gauge and the air permeability position are controlled to remain unchanged, and the chain disk is slowly started to obtain the longitudinal thickness and longitudinal air permeability.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] High degree of automation: fully automated testing of diaphragm performance is achieved, reducing manual intervention and improving testing efficiency. The data of horizontal and vertical consistency can be clearly seen for each roll.

[0026] High detection accuracy: High-precision sensor detection ensures the accuracy of the test results.

[0027] Real-time monitoring and early warning: It has real-time monitoring and abnormal early warning functions to ensure the stable operation of the production line.

[0028] Improve product quality: Through strict quality control, ensure that each batch of separators meets the specified performance standards and improve the overall performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the automatic detection device of the present invention;

[0030] Figure 2 It is a schematic diagram of the structure of a thickness detection unit of the automatic detection device of the present invention;

[0031] Figure 3 Schematic diagram of a puncture strength detection unit structure element of the automatic detection device of the present invention;

[0032] Figure 4 It is a schematic diagram of the structure of the air permeability detection unit of the automatic detection device of the present invention;

[0033] Figure 5 It is a schematic diagram of the mechanical arm structure of the automatic detection device of the present invention.

[0034] Markings in the figure are: 1-mother roll roller, 2-guide roller, 3-meter meter, 4-cutter, 5-drive motor, 6-chain plate, 7-clamp, 8-mechanical clamp closer, 9-slide rail, 10-thickness gauge, 11-infrared width measuring instrument, 12-support platform, 13-mechanical arm, 14-weighing sensor, 15-puncture strength detection unit, 16-air permeability detection unit, 17-screw, 18-fixed rod, 19-fixed plate, 20-base, 21-upper arm, 22-lower arm, 23-mechanical claw cylinder, 24-mechanical claw, 25-slide rail, 26-base, 27-needle, 28-dynamometer, 29-standard gasket, 30-vent, 31-cylinder. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown, an automatic detection device for the performance of lithium-ion battery separators is located between primary slitting and winding, and is mainly composed of a feeding mechanism and a detection module. The feeding mechanism is responsible for feeding the cut separators into each detection module; the detection module includes a thickness detection unit, a gram weight detection unit, a porosity detection unit, an air permeability detection unit, and a puncture strength detection unit.

[0037] Feeding mechanism: located at the starting end of the frame, responsible for feeding the cut diaphragm into the detection module. The feeding mechanism includes an unwinding device and a conveying device, which are used to ensure that the diaphragm enters the detection area smoothly and without tension. Among them, the unwinding device is composed of a mother roll roller 1, a guide roller 2, a meter 3 and a cutter 4. The diaphragm passes through the guide roller from the mother roll. When the unwinding device unwinds a certain number of meters of diaphragm, the cutter 4 automatically starts to cut the diaphragm. In order to facilitate transmission, an existing conveying device is added, which includes: a chain disk 6, a drive motor 5 of the chain disk, a clamp 7 set on the chain disk, a mechanical clamp closer 8 and a slide rail 9. Among them, the clamps are distributed at both ends of the film along its length direction, and they can reciprocate along the length direction of the chain disk; and the number of clamps can be increased or decreased according to the actual needs of the product. The mechanical clamp closer can control the opening and closing of the clamp, and the chain disk can move perpendicular to the length direction according to the width of the film through the slide rail. After unwinding is completed, a slitting is performed, and at the same time, the cut diaphragm is translated into the detection module through the chain disk for detection.

[0038] Detection modules: They are arranged on the frame, including thickness detection unit, gram weight detection unit, porosity detection unit, air permeability detection unit and puncture strength detection unit. The diaphragm can pass through each detection point continuously and sequentially through the guide rail.

[0039] Thickness detection unit: Figure 2 As shown, the thickness detection uses a thickness gauge 10, which is driven by a slide rail 25 to reciprocate in the width direction of the diaphragm to ensure accurate and lossless measurement, and the measurement results are fed back to the central control computer. The thickness gauge can use the existing Skende thickness gauge on the production line.

[0040] Gram weight detection unit: Combine the weighing sensor and the area measuring device to calculate the weight of the diaphragm per unit area, i.e., the gram weight. The area measuring device consists of a meter counter 3 and an infrared width measuring instrument 11. The meter counter calculates the number of unwinding meters by the number of unwinding turns. The width measuring device detects the width of the film by infrared rays. The length multiplied by the width is the area of ​​the film. The weighing sensor is located at the very end of the detection. After the film reaches the final end, the clamp is automatically opened by the mechanical clamp closer, and the film is gently stacked on the support 12. Then the mechanical arm 13 clamps the middle of the stacked film and sends it to the weighing sensor 14 for weighing. The weight of the diaphragm per unit area is fed back to the central control computer. Figure 5 The robot arm includes a screw 17, a fixed rod 18, a fixed plate 19, a base 20, a large arm 21, a small arm 22, a mechanical claw cylinder 23 and a mechanical claw 24. The total length of the robot arm is 1004.03 mm, and the total height is 730.07 mm. The robot arm fixes the large arm through two fixed plates and four fixed rods. The motor in the base drives the screw to rotate the rod to realize the up and down movement of the large arm. The large arm motor drives the synchronous belt to drive the synchronous wheel in the small arm to realize the left and right swing of the small arm. The mechanical claw realizes the grasping action through the extension and contraction of the cylinder.

[0041] Puncture strength detection unit: Figure 3 As shown, the diaphragm passes between the base 26 and the needle 27. The measuring device is located behind the thickness gauge. The diaphragm is penetrated by the standard needle 27 at a standard speed. There is a dynamometer 28 above the needle 27, which can capture the maximum load (N) at the moment of penetration. The load divided by the average thickness (μm) of the diaphragm is the puncture strength (N / μm). The measured value is fed back to the central control computer.

[0042] Air permeability testing unit: Figure 4 As shown, the air pressure is provided by a cylinder 31 with a specific diameter and standard weight. The upper gasket can slide freely in the outer cylinder filled with sealing oil. There is a connecting air pipe inside the gasket, which can deliver air for a fixed time. The amount of gas passing through a fixed time is converted by calculating the pressure difference before and after delivery, which can be converted into the time required for 100cc of air to pass through a diaphragm of a specific area. The diaphragm is sandwiched between standard gaskets 29, and the center of the gasket has a vent 30 to allow gas to flow through to evaluate the air permeability, and the measured value is fed back to the central control computer.

[0043] Porosity detection unit: Combined with the diaphragm weight and thickness, the porosity is calculated according to porosity = (pure PE density - diaphragm weight per unit area / average diaphragm thickness) / pure PE density * 100%, and directly fed back to the central control computer.

[0044] The method for testing the performance of lithium-ion battery separator based on the above automatic testing device includes:

[0045] Feeding stage: The unwinding device unwinds the wound diaphragm. When the set length is reached, the automatic film cutting knife is activated, the chain clamp clamps the cut film, and the diaphragm is smoothly fed into the detection module through the conveyor belt.

[0046] Testing stage: The membrane passes through the thickness testing unit, gram weight testing unit, porosity testing unit, air permeability testing unit and puncture strength testing unit. Each testing unit performs corresponding performance tests on the membrane, and transmits the data to the central control computer in real time and displays a detailed test report, including the test results and qualified judgment of various performance indicators. If abnormal data is found, the alarm device will immediately sound an alarm and suspend the production line.

[0047] The specific detection steps are as follows:

[0048] Step 1: After the main line is wound up, move the mother roll to the front of the guide roll.

[0049] Step 2, send the joint of the diaphragm to the clamp of the conveyor, move the width of the chain disc along the vertical direction of the diaphragm according to the width of the film, set the unwinding meter to 20m, and then start the equipment.

[0050] Step 3: The chain disk runs at 5m / min, and the diaphragm is continuously clamped. After the unwinding length reaches 20m, the unwinding roller and the chain disk stop, and the cutter starts automatically, cutting along the vertical direction of the diaphragm to cut the diaphragm.

[0051] Step 4, start the infrared width measuring instrument to measure the diaphragm width.

[0052] Step 5, start the thickness gauge and measure the thickness. When measuring the longitudinal consistency of the thickness, the thickness gauge can be controlled to remain unchanged and the chain disk can be slowly started to obtain the longitudinal thickness.

[0053] Step 6, start the air permeability tester to measure the air permeability value of the membrane. When measuring the longitudinal consistency of the air permeability value, the air permeability position can be controlled to remain unchanged, and the chain disk can be slowly started to obtain the longitudinal air permeability consistency test data.

[0054] Step 7, start the acupuncture machine and measure the diaphragm puncture strength.

[0055] Step 8, after the measurement is completed, the chain disc starts, the clamp gradually opens, and the diaphragm is accumulated on the support table.

[0056] Step 9: After all the clamps are opened, the robot arm starts, grabs the middle of the diaphragm and sends it to the weighing hopper for weighing. The gram weight is obtained by multiplying the length by the width.

[0057] Step 10, combining the diaphragm weight and thickness, combined with the diaphragm area and thickness, according to the porosity (%) = (pure PE density - diaphragm weight per unit area / average thickness) / pure PE density * 100%, where pure PE density = 0.95, calculate the porosity and directly feed back to the central control computer.

[0058] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the protection scope of the present invention in any form, and all technical solutions obtained by equivalent replacement and the like fall within the protection scope of the present invention. The parts not involved in the present invention are the same as the prior art or can be implemented by the prior art.

Claims

1. An automatic detection device for the performance of lithium-ion battery diaphragm, comprising a feeding mechanism and a detection module, wherein the feeding mechanism is used to feed the cut diaphragm into the detection module; characterized in that: The detection module includes a thickness detection unit, a gram weight detection unit, a porosity detection unit, a puncture strength detection unit and an air permeability detection unit.

2. The automatic detection device for lithium-ion battery diaphragm performance according to claim 1, characterized in that: The feeding mechanism is located at the starting end of the frame, and includes a reeling device and a conveying device; the reeling device includes a mother roll roller, a guide roller, a meter counter and a cutter. The diaphragm passes through the mother roll roller through the guide roller and the unwinding length is measured by the meter counter. When the reeling reaches a certain number of meters, the cutter automatically starts to cut the diaphragm.

3. The automatic detection device for lithium-ion battery diaphragm performance according to claim 2, characterized in that: The conveying device is arranged on both sides of the frame, and includes a chain disk, a driving motor of the chain disk, a clamp arranged on the chain disk, a mechanical clamp closer and a slide rail. The clamps are distributed at both ends of the diaphragm along the length direction of the chain disk. The mechanical clamp closer is used to control the opening and closing of the clamps. The chain disks on both sides are manually adjusted by buttons according to the width of the diaphragm to move closer to or away from each other on the slide rail. After that, the cut diaphragm is translated into the detection module through the chain disk for detection.

4. The automatic detection device for lithium-ion battery diaphragm performance according to claim 1, characterized in that: The thickness detection unit uses a thickness gauge to detect the thickness of the diaphragm; the thickness gauge is slidably installed on the gantry through a guide rail, and the thickness gauge reciprocates in the width direction of the diaphragm through the guide rail, and its measurement result is fed back to the central control computer.

5. The automatic detection device for lithium-ion battery diaphragm performance according to claim 1, characterized in that: The gram weight detection unit includes a weighing sensor and an area measuring device, and the weight of the diaphragm per unit area is calculated by the measured weight and area; the area measuring device is composed of a meter counter and an infrared width measuring instrument, the meter counter calculates the number of unwinding meters by the number of unwinding turns, and the infrared width measuring instrument detects the width of the diaphragm by infrared rays, and the area of ​​the membrane is obtained by multiplying the length by the width, and the measurement result is fed back to the central control computer; the weighing sensor is located at the final end of the device, and a support platform and a mechanical arm are provided above the weighing sensor. The support platform is L-shaped, and includes a horizontal platform and a vertical baffle. The baffle is located at the rear end of the platform, and is used to block the diaphragm transported here and stack it on the platform. The mechanical arm is used to clamp the stacked diaphragm and send it to the weighing sensor for weighing, and the weight after weighing is fed back to the central control computer.

6. The automatic detection device for lithium-ion battery diaphragm performance according to claim 1, characterized in that: The porosity detection unit combines the gram weight and thickness of the diaphragm and calculates the porosity according to porosity = (pure PE density - gram weight of diaphragm per unit area / average thickness of diaphragm) / pure PE density * 100%, and the measured value is fed back to the central control computer.

7. The automatic detection device for lithium-ion battery diaphragm performance according to claim 1, characterized in that: The puncture strength detection unit includes a puncture base and a needle that are arranged opposite to each other. The septum passes through the puncture base and the needle. The needle penetrates the septum at a standard speed. A dynamometer is arranged on the needle to capture the maximum load at the moment of penetration. The maximum load is divided by the average thickness of the septum, which is the puncture strength. The measured values ​​are fed back to the central control computer.

8. The automatic detection device for lithium-ion battery diaphragm performance according to claim 1, characterized in that: The air permeability detection unit uses the time required for air to pass through a membrane of a specific area to evaluate the air permeability; the air permeability detection unit includes two gaskets arranged opposite to each other, with a vent hole in the center of the gasket allowing gas to flow through, and an air pipe is connected inside the gasket to transport air. The amount of gas passing through in a fixed time is converted by calculating the pressure difference before and after transportation.

9. A method for testing the performance of a lithium-ion battery separator using the automatic testing device according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: After the main line is wound up, the mother roll is transferred to the front of the guide roll; Step 2, delivering the joint of the diaphragm to the clamp of the conveying device, and adjusting the width of the chain disk along the vertical direction of the diaphragm according to the width of the diaphragm, and then closing the clamp; Step 3: The chain disk runs at a certain speed. During the operation, the diaphragm is continuously clamped. When the unwinding length reaches the set value, the unwinding roller and the chain disk stop. At this time, the cutter starts automatically and cuts along the vertical direction of the diaphragm to cut the diaphragm. Step 4, start the infrared width measuring instrument to measure the diaphragm width; Step 5, start the thickness gauge to measure the thickness; Step 6, starting the air permeability detection unit to measure the air permeability value of the diaphragm; Step 7, starting the puncture strength detection unit, the needle runs through the septum at a standard speed, and the septum puncture strength is measured; Step 8: After the measurement is completed, the chain disc starts, the clamp gradually opens, and the diaphragm is accumulated on the support table; Step 9: After all the clamps are opened, the mechanical arm starts, grabs the middle position of the diaphragm and sends it to the weighing hopper for weighing; Step 10, the central control computer summarizes the data to obtain the thickness, weight, porosity, puncture strength and air permeability of the diaphragm.

10. A method for detecting performance of a lithium-ion battery separator according to claim 9, characterized in that: During the measurement process, if the longitudinal consistency of thickness and air permeability needs to be measured, the thickness gauge and air permeability positions are controlled unchanged, and the chain disk is slowly started to obtain the longitudinal thickness and longitudinal air permeability.

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