Lithium battery separator extraction and drying apparatus and method

Abstract

This invention discloses a lithium battery separator extraction and drying apparatus and method. The lithium battery separator extraction and drying apparatus includes an extraction device. Along the separator's transmission direction, a spray purification device, a gradient pre-drying device, and a suspension drying device are sequentially arranged after the extraction device. This invention improves the surface cleanliness of the separator before drying and reduces the amount of liquid on the separator surface through multi-stage spray purification equipment; it achieves gradient drying using pre-drying rollers combined with separator suspension drying to achieve uniform drying of the extractant; and it uses a dehumidification device to remove water vapor in the drying chamber, reducing the humidity of the drying chamber space and reducing water stains at the source, thus significantly reducing water stain defects in lithium battery separators and significantly improving the overall quality of separator products. This invention adopts a combination of multi-stage spray purification, gradient drying, and suspension drying processes, starting from improving the uniformity of liquid on the separator and the uniformity of drying, to achieve a separator preparation effect free of water stain defects.

Description

Technical Field

[0001] This invention relates to a lithium battery separator extraction and drying apparatus and method, belonging to the technical field of lithium battery separator production equipment. Background Technology

[0002] In existing technologies, the lithium battery separator extraction process generally employs a process scheme combining a scraping roller and an extraction tank overflow system: the scraping roller reduces the amount of liquid carried on the separator, while the overflow system improves the cleanliness of the liquid carried on the separator. However, this process has significant technical drawbacks. First, the scraping system has poor operational stability, cannot completely remove the extractant carried on the separator surface, and is difficult to guarantee the uniformity of liquid on both sides of the separator. Second, during the operation of the overflow system, foreign matter and impurities easily accumulate at the bottom of the tank. When the separator is running, these impurities are easily drawn into the scraping system. After long-term operation, these impurities can scratch the separator, severely affecting the microstructure of the separator product and further exacerbating the problem of uneven liquid carry-on.

[0003] Meanwhile, existing technologies often employ roller drying devices for diaphragm drying. The rollers are heated by circulating water, and heat is transferred to the diaphragm through the roller surface. However, gaps exist between the rollers, preventing continuous heating and drying of the diaphragm. Furthermore, the circulating water inside the rollers flows in a spiral pattern during operation, resulting in uneven distribution. The intermittent contact between the diaphragm and rollers leads to short contact times, resulting in poor drying uniformity and low drying efficiency. Ultimately, this easily causes water stains on the diaphragm surface, affecting product quality. A photograph of a diaphragm with water stain defects from existing technologies is shown below. Figure 1 As shown in the image, the reflective area clearly reveals the water stain defect. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium battery separator extraction and drying apparatus and method to solve the technical problems of uneven liquid distribution, low cleanliness, poor drying effect, and easy formation of water stains on the separator in the existing lithium battery separator extraction and drying process.

[0005] The lithium battery separator extraction and drying apparatus of the present invention adopts the following technical solution: A lithium battery separator extraction and drying apparatus includes an extraction device. Along the separator conveying direction, a spray purification device, a gradient pre-drying device, and a suspension drying device are sequentially arranged after the extraction device. The spray purification device includes a small drying chamber, in which a traction guide roller is arranged to move the separator laterally. Spray devices are respectively arranged above and below the separator, and scraping devices are respectively arranged on the upper and lower sides of the separator. A vacuum suction roller is arranged after the last traction guide roller, and the liquid on the separator is adsorbed when the separator passes through the vacuum suction roller. The gradient drying device includes a vacuum... The drying equipment includes a pre-drying chamber following the liquid suction roller and pre-drying rollers arranged vertically within the drying chamber. The pre-drying rollers are spaced vertically within the pre-drying chamber, and their temperature gradually increases along the direction of membrane movement. Air knives are provided on both sides of the membrane, and an exhaust zone is provided on the wall of the pre-drying chamber. The suspended drying equipment includes a drying chamber, a drying chamber traction roller, and a clamping mechanism for holding both sides of the membrane. The membrane moves laterally parallel to the horizontal plane within the drying chamber under the guidance of the drying chamber traction roller. Heating devices for heating the membrane are provided on both the upper and lower sides of the membrane within the drying chamber, and a dehumidification device is also provided within the drying chamber.

[0006] The extraction equipment includes extraction tanks arranged in series. Each adjacent extraction tank has a membrane outlet and an overflow outlet. The overflow direction of the overflow outlet is opposite to the diaphragm running direction, and the height of the overflow outlet gradually increases along the diaphragm running direction. The liquid height in the extraction tank changes synchronously with the overflow outlet height, and the extractant overflows in the extraction tank in a counter-gradient manner. The bottom of the small drying chamber is connected to the last extraction tank through a liquid delivery pipeline. The liquid delivery pipeline is equipped with a drain valve and a liquid inlet valve. A diaphragm pump and a filter device are installed between the drain valve and the liquid inlet valve.

[0007] The lithium battery separator extraction and drying device also includes a wind pressure / temperature and humidity detection component, specifically: a wind pressure meter and a temperature and humidity meter are installed above the spray device in the small drying chamber; a wind pressure meter and a temperature and humidity meter are installed above the uppermost pre-drying roller in the pre-drying chamber; a wind speed meter and a wind direction meter are installed above and below the membrane outlet of the drying chamber between the pre-drying chamber and the drying chamber; a wind pressure meter and a temperature and humidity meter are installed at the top of the drying chamber and near the membrane outlet.

[0008] There are two or more traction guide rollers, each driven by an independent drive motor. On the diaphragm running path between the traction guide rollers, when the diaphragm exits the traction guide roller above the diaphragm, a spraying device and a scraping device are set above and below the diaphragm. When the diaphragm exits the traction guide roller below the diaphragm, a spraying device is set only below the diaphragm. The spraying device is arranged near the traction guide roller at the front of the diaphragm running direction, and the spray nozzle of the spraying device extends more than 5 cm on each side of the diaphragm width.

[0009] The small drying chamber and the pre-drying cavity are integrated into one unit, forming an L-shaped structure. The exhaust area is located on the upper side of the pre-drying area. The diaphragm is driven upward in the drying cavity. Pure water at 25-40℃ is introduced into the pre-drying roller, and the diaphragm is heated by heat transfer. The temperature difference between adjacent pre-drying rollers is 1-2℃.

[0010] Each pre-drying roller is equipped with an air knife, and the number of air knives on both sides of the diaphragm is equal. The air knives are connected to a blower, a drying filter, and a high-pressure variable frequency air supply fan. The blower draws in outside air, which is heated and filtered by the drying filter, and then pressurized and delivered as clean air at 30-40°C by the high-pressure variable frequency air supply fan. The clean air is blown onto the diaphragm surface through the air knives. At least one high-pressure variable frequency air supply fan is provided, with a total rated air volume ≥3000m³ / h and an output air pressure controlled at 3000Pa~4000Pa. Angle adjustment devices are provided on both sides of the air knives to adjust the angle between the air knives and the diaphragm.

[0011] The clamping mechanism includes a chain disc, a pivot pin, and a chain clamp. The chain disc drives the pivot pin and the chain clamp that clamps the sides of the diaphragm. The chain clamp is used to clamp the edges of both sides of the diaphragm. Four heating devices are arranged above and below the drying chamber, and the length of each heating device completely covers the width of the diaphragm. The dehumidification device is a rotary dehumidification device.

[0012] The lithium battery separator extraction and drying method of the present invention adopts the following technical solution: A lithium battery separator extraction and drying method, which is carried out using the above-mentioned lithium battery separator extraction and drying device, includes the following steps: (1) Extraction overflow process: the separator is extracted by the extractant in the extraction tank of the extraction device; (2) Spray purification process: the separator after extraction enters the small drying room, the membrane surface carries a large amount of extractant, after the smooth surface and matte surface of the separator are sprayed by the spray device, the liquid on the surface of the separator is scraped off by the scraping device, and the vacuum suction roller is vacuumed by the blower to adsorb the liquid on the surface of the separator; (3) Gradient pre-drying process: the separator carrying high purity uniform extractant enters the The pre-drying chamber contacts the pre-drying roller, and the extractant inside the diaphragm is initially volatilized through heat transfer. The temperature of the pre-drying roller increases in a gradient along the direction of diaphragm operation to ensure uniform volatilization of the extractant. At the same time, the air knife blows purified and heated clean air to both sides of the diaphragm to achieve uniform pre-drying of the extractant remaining on the membrane surface. (4) Suspension drying process: The pre-dried diaphragm is pulled to the clamping mechanism by the drying oven traction roller. The clamping mechanism clamps the sides of the diaphragm to achieve suspension transport of the diaphragm. The heating devices above and below the diaphragm provide bidirectional full-coverage heating to achieve uniform and complete drying of the extractant remaining on the membrane surface. At the same time, the dehumidification device extracts water vapor and volatilized extractant from the drying oven.

[0013] In step (1), the overflow direction of the extractant is opposite to the running direction of the diaphragm. The new extractant is injected from the last stage extraction tank 1 and overflows in reverse through the overflow port with a height gradient along the running direction. In step (2), the extraction waste liquid accumulated at the bottom of the small drying room is extracted by the diaphragm pump, filtered to remove impurities, and then returned to the extraction tank for recycling.

[0014] In step (3), after the airflow blown by the air knife onto the diaphragm is pre-dried, it enters the exhaust zone in the opposite direction of the diaphragm's operation and is finally discharged from the pre-drying chamber through the exhaust pipe.

[0015] The wind pressure, temperature and humidity inside the small drying room, pre-drying chamber and drying room are monitored in real time using a wind pressure meter and a temperature and humidity meter; the wind speed and direction at the film outlet of the drying room are monitored in real time using an anemometer and a wind direction meter.

[0016] The beneficial effects of this invention are as follows: This invention improves the surface cleanliness of the separator before drying and reduces the amount of liquid on the separator surface through multi-stage spray purification equipment; it achieves gradient drying using pre-drying rollers combined with separator suspension drying to achieve uniform drying of the extractant; and it uses a dehumidification device to remove water vapor in the drying chamber, reducing the humidity of the drying chamber space and reducing water stains at the source, thus significantly reducing water stain defects in lithium battery separators and significantly improving the overall quality of the separator product. This invention employs a combined process of multi-stage spray purification, gradient drying, and suspension drying, improving both the uniformity of liquid on the separator and the uniformity of drying, to achieve a separator preparation effect free of water stain defects.

[0017] As a preferred option, the extraction equipment adopts a multi-stage overflow tank system to ensure the basic cleanliness of the diaphragm when it enters the small drying room with liquid, and further removes impurities from the extractant on the diaphragm surface.

[0018] As a preferred solution, the extraction waste liquid accumulated at the bottom of the small drying chamber is filtered and purified before being returned to the extraction tank, thereby realizing the recycling of the extraction liquid and reducing its consumption.

[0019] As a preferred solution, wind pressure / temperature and humidity detection components enable real-time visual monitoring of wind field, temperature and humidity, wind speed, and wind direction, ensuring the stable operation of various process parameters and providing data support for process optimization. As a preferred embodiment, the present invention optimizes the layout and operation process of the scraping device, thereby reducing the amount of extract carried by the diaphragm, improving the uniformity of liquid on both sides of the diaphragm, improving the microstructure of the diaphragm, enhancing the structural consistency of both sides of the diaphragm, and optimizing the uniformity of the hole diameter structure on both sides.

[0020] As a preferred option, the rotary dehumidifier is an adsorption-type dry dehumidification device. The internal honeycomb moisture-absorbing rotary wheel rotates continuously, completing adsorption dehumidification in the treatment zone and the regeneration zone. The air is adsorbed in the heat regeneration treatment zone and then enters the regeneration zone after saturation, where the moisture is desorbed and discharged. Attached Figure Description

[0021] Figure 1 The image shows a photograph of a diaphragm with water stain defects from existing technology. Figure 2 These are electron microscope images of diaphragms with water stain defects from existing technology; Figure 3 This is a schematic diagram of a lithium battery separator extraction and drying apparatus according to an embodiment of the present invention; Figure 4 yes Figure 3 A schematic diagram of the clamping mechanism holding the diaphragm; Figure 5 The image shows a photograph of a stain-free diaphragm produced using this invention. Figure 6 These are electron microscope images of the stain-free diaphragm produced using this invention; Figure 7 This is a comparison chart showing the quantity of water-free membranes produced using this invention and water-free membranes produced using existing technologies.

[0022] Figure 3 and Figure 4 Components: 1-Extraction tank; 2-Membrane inlet; 3-Overflow outlet; 4-Extractant; 5-Diaphragm; 6-Small drying chamber; 7-Guiding roller; 8-Pre-drying roller; 9-Inlet valve; 10-Diaphragm pump; 11-Filter device; 12-Scraping device; 13-Spraying device; 14-Temperature and humidity meter; 15-Air pressure meter; 16-Air knife; 17-Anemometer; 18-Wind direction indicator; 19-Heating device; 20-Suspension drying device; 200-Shaft pin and chain clamp; 201-Chain disc; 21-Drying chamber; 22-Dehumidification device; 23-Drying chamber traction roller; 24-Exhaust area; 25-Vacuum suction roller; 26-Drain valve; 27-Infusion pipeline. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0024] As shown in the figure, a lithium battery separator extraction and drying device according to an embodiment of the present invention includes an extraction device, and along the separator transmission direction, a spray purification device, a gradient pre-drying device, and a suspension drying device are sequentially arranged after the extraction device.

[0025] The extraction equipment includes extraction tanks 1 arranged in series. There are usually 8-10 extraction tanks 1. Each adjacent extraction tank 1 has a membrane outlet 2 and an overflow outlet 3. The overflow direction of the overflow outlet 3 is opposite to the running direction of the diaphragm 5, and the height of the overflow outlet 3 gradually increases along the running direction of the diaphragm 5. The liquid height in the extraction tank 1 changes synchronously with the height of the overflow outlet 3. The extractant overflows in the extraction tank 1 in a counter-gradient manner to ensure the cleanliness of the extractant 4 in the downstream section of the extraction tank 1 and reduce the impurity content on the membrane surface when the diaphragm 5 enters the small drying room 6 with liquid carried from the extraction tank 1.

[0026] The spray purification equipment includes a small drying chamber 6, inside which a traction guide roller 7 is installed to move the diaphragm 5 laterally. Spray devices 13 are installed above and below the diaphragm 5, and scraping devices 12 are installed on the upper and lower sides of the diaphragm 5. After the last traction guide roller 7, a vacuum suction roller 25 is installed. When the diaphragm passes through the vacuum suction roller 25, the liquid on the diaphragm is adsorbed. The spray purification equipment directly purifies the extractant on the surface of the diaphragm 5 entering the small drying chamber 6, maximizing the cleanliness of the liquid on the diaphragm 5, while reducing the amount of liquid and improving the uniformity of liquid.

[0027] There are two or more traction guide rollers 7, each driven by an independent drive motor (to avoid diaphragm tension fluctuations, the diameter of each traction roller should be kept as equal as possible); the running speed of each traction roller is kept consistent to avoid stretching or displacement of the diaphragm 5 during operation; the spray device 13 and the scraper device 12 are set at the exit position of the diaphragm 5, specifically: on the diaphragm running path between the traction guide rollers 7, when the diaphragm exits the traction guide roller 7 above the diaphragm, the spray device and the scraper device are set above and below the diaphragm; when the diaphragm exits the traction guide roller 7 below the diaphragm, the spray device is set only below the diaphragm; the spray device 13 is arranged near the traction guide roller 7 at the front of the diaphragm running direction, and the length of the spray nozzle of the spray device 13 extends more than 5cm on each side of the diaphragm width (preferably 20cm), to achieve full coverage spraying of the diaphragm 5 surface. Through a continuous process of multi-stage spraying, scraping, and vacuum adsorption, the amount of liquid on the membrane surface before drying of the diaphragm 5 is continuously reduced, and the cleanliness of the membrane surface is improved.

[0028] The bottom of the small drying chamber 6 is connected to the final extraction tank via a liquid delivery pipeline 27. The pipeline 27 is equipped with a drain valve 26 and an inlet valve 9. A diaphragm pump 10 and a filter device 11 are located between the drain valve 26 and the inlet valve 9. The extractant (including spray waste liquid and membrane scraping liquid) accumulated at the bottom of the small drying chamber 6 is extracted by the diaphragm pump 10, filtered to remove impurities, and then returned to the final extraction tank 1 for recycling. This achieves both the recovery and reuse of the extractant and prevents impurities at the bottom of the small drying chamber 6 from contaminating the extractant in the extraction tank 1.

[0029] The gradient drying device includes a pre-drying chamber located after the vacuum suction roller 25 and pre-drying rollers 8 arranged vertically within the pre-drying chamber. The pre-drying rollers 8 are spaced vertically within the pre-drying chamber, and their temperature gradually increases along the direction of the diaphragm's movement. Air knives 16 are provided on both sides of the diaphragm, and an exhaust zone 24 is provided on the wall of the pre-drying chamber. The diaphragm moves upward within the pre-drying chamber, and pure water at 25-40°C is introduced into the pre-drying rollers 8 to heat the diaphragm through heat transfer. The temperature difference between adjacent pre-drying rollers 8 is 1-2°C, and the gradient heating of the pre-drying rollers 8 ensures uniform evaporation of the extractant. Each pre-drying roller 8 is equipped with an air knife 16, and the number of air knives on both sides of the diaphragm is equal. In this embodiment, two air knives 16 are arranged on the smooth surface and two on the matte surface of the diaphragm 5. The air knife 16 is connected to a blower, a drying filter, and a high-pressure variable frequency air supply fan (not shown in the attached figure). The blower draws in outside air, which is heated and filtered by the drying filter. The high-pressure variable frequency air supply fan pressurizes and delivers clean air at 30-40°C. The clean air is blown onto the diaphragm surface through the air knife to achieve uniform pre-drying of the residual extractant on the membrane surface. At least one high-pressure variable frequency air supply fan is provided, with a total rated air volume ≥3000m³ / h and an output air pressure controlled at 3000Pa~4000Pa. Online angle adjustment devices (not shown in the attached figure) are provided on both sides of the air knife 16 to adjust the angle between the air knife 16 and the diaphragm in real time to optimize the pre-drying effect.

[0030] The small drying chamber 6 and the pre-drying chamber are integrated into one unit, forming an L-shaped structure. The exhaust zone is located on the upper side of the pre-drying zone. After the airflow blown by the air knife 16 onto the diaphragm 5 completes the pre-drying, it enters the exhaust zone 24 in the opposite direction of the diaphragm 5 and is finally discharged from the small drying chamber 6 through the exhaust pipe, thus preventing the accumulation of humid airflow in the drying chamber 21.

[0031] The suspended drying equipment includes a drying chamber 21, a drying chamber traction roller 23 disposed within the drying chamber 21, and a clamping mechanism for holding the two sides of the diaphragm. The diaphragm moves laterally parallel to the horizontal plane within the drying chamber under the guidance of the drying chamber traction roller 23. Heating devices for radiant heating of the diaphragm are respectively located on the upper and lower sides of the diaphragm within the drying chamber. A dehumidification device is also provided within the drying chamber. The clamping mechanism includes a chain, a shaft pin, and chain clamps. The chain drives the shaft pin and the chain clamps holding the edges of the diaphragm. The chain clamps are used to hold the edges of the diaphragm on both sides. Multiple heating devices are arranged above and below the drying chamber, each heating device's length completely covering the width of the diaphragm, and adjacent heating devices are in contact with each other. The suspended diaphragm 5 is heated through bidirectional thermal radiation, improving the drying uniformity of the diaphragm 5 and extending the effective drying time. Simultaneously, the thermal radiation heating device 19 heats the internal space of the drying chamber 21, ensuring the stability of the thermal environment of the diaphragm 5 and further optimizing the drying effect. The dehumidification device 22 is a rotary dehumidifier. The water vapor generated in the drying chamber 21 during the drying process is extracted and removed in real time by the rotary dehumidifier 22, which prevents water vapor from condensing and dripping onto the surface of the diaphragm 5, thereby reducing the occurrence of water stain defects on the diaphragm 5 from the source.

[0032] The lithium battery separator extraction and drying device also includes a wind pressure / temperature and humidity detection component. Specifically, a wind pressure meter 15 and a temperature and humidity meter 14 are installed above the spray device 13 inside the small drying chamber 6; a wind pressure meter 15 and a temperature and humidity meter 14 are installed above the uppermost pre-drying roller 8 inside the pre-drying chamber; an anemometer 17 and a wind direction meter 18 are installed above and below the membrane outlet of the drying chamber between the pre-drying chamber and the drying chamber 21; a wind pressure meter 15 and a temperature and humidity meter 14 are installed at the top and near the membrane outlet inside the drying chamber 21. The wind pressure / temperature and humidity detection component enables real-time visual monitoring of the changes in airflow, temperature, and humidity inside the equipment, providing data support for process parameter adjustment. Through the coordinated work of various detection instruments, real-time data on wind pressure, temperature, humidity, wind speed, and wind direction inside the equipment are collected, achieving precise control of airflow and temperature and humidity, and ensuring the stable operation of the purification and drying processes.

[0033] This invention achieves water-free preparation of lithium battery separators through the coordinated operation of extraction equipment, spray purification equipment, gradient pre-drying equipment, suspension drying equipment, and wind pressure / temperature and humidity detection components. The steps of the lithium battery separator extraction and drying method of this invention are as follows: (1) Extraction overflow process: The diaphragm is extracted by the extractant in the extraction tank of the extraction device; the diaphragm 5 enters the extraction tank 1 from the membrane port 2 and is extracted by the extractant 4 in the extraction tank 1. The overflow direction of the extractant 4 is opposite to the running direction of the diaphragm 5. The new extractant is injected from the last stage extraction tank 1 and overflows in reverse through the overflow port with a height gradient along the running direction, ensuring that the extractant 4 in the later stage of extraction always maintains high cleanliness and reducing the impurity content of the liquid carried by the diaphragm 5; In this embodiment, 8 extraction tanks are used, and the overflow port height of the extraction tanks 1 to 8 increases in a gradient, ensuring that new liquid can be introduced into the tank 8 and overflows forward (tank 7) when the liquid level reaches the overflow port height, ensuring the cleanliness of the liquid at the back end. The height difference of the overflow port of the adjacent extraction tanks is 5-10cm.

[0034] (2) Multi-stage spray purification process: The extracted diaphragm enters the small drying room 6. The membrane surface carries a large amount of extractant. After the smooth and matte surfaces of the diaphragm are sprayed by the spray device, the liquid on the surface of the diaphragm is scraped off by the scraping device. The vacuum suction roller 25 generates a vacuum by drawing out the liquid inside the vacuum roller 25, and adsorbs the liquid on the surface of the diaphragm.

[0035] After multi-stage spray purification by the spray purification equipment, both the smooth and matte surfaces of the diaphragm 5 undergo two rounds of extractant spraying and uniform liquid scraping. The matte surface is further dehydrated by gravity and the friction of the guide roller 7. Then, it is vacuum-adsorbed by the vacuum suction roller 25. The vacuum suction roller 25 generates a vacuum through a blower. The roller surface is covered with felt, and the liquid is adsorbed into the liquid delivery pipeline by the internal vacuum of the felt. Finally, only high-purity and uniformly distributed extractant that cannot be removed by physical means remains on the surface of the diaphragm 5, achieving a triple improvement in liquid volume, liquid uniformity, and cleanliness.

[0036] In this step, the extraction waste liquid accumulated at the bottom of the small drying room is extracted by a diaphragm pump, filtered to remove impurities, and then returned to the extraction tank for recycling, thereby achieving extraction agent recovery and impurity isolation.

[0037] (3) Gradient pre-drying process: The diaphragm 5 carrying high-purity uniform extractant enters the pre-drying chamber and contacts the pre-drying roller 8. The extractant in the diaphragm is initially volatilized through heat transfer. The temperature of the pre-drying roller 8 increases in a gradient along the running direction of the diaphragm to ensure uniform volatilization of the extractant. At the same time, the air knife 16 blows purified and heated clean air to both sides of the diaphragm to achieve uniform pre-drying of the extractant remaining on the membrane surface. After the airflow blown by the air knife 16 to the diaphragm completes the pre-drying, it enters the exhaust zone 24 in the opposite direction of the diaphragm's running direction and is finally discharged from the pre-drying chamber through the exhaust pipe.

[0038] The pre-drying roller 8 is heated by electric heating water inside; the number of pre-drying rollers 8 can be increased or decreased as needed, usually controlled at ≥3. If the number is less than 3, the drying effect will be significantly weakened; the temperature range of the pre-drying roller 8 is 25-40℃. If it is below this range, the roller is prone to freezing, and if it is above this range, other diaphragm defects will occur; the temperature gradient is set at 1-3℃.

[0039] (4) Suspension drying process: The pre-dried diaphragm is pulled to the clamping mechanism by the drying oven traction roller 23. The clamping mechanism clamps the sides of the diaphragm to achieve suspension conveying of the diaphragm. The heating device 19 above and below the diaphragm provides bidirectional full-coverage heating to achieve uniform and complete drying of the extractant remaining on the diaphragm surface. At the same time, the dehumidification device 22 extracts water vapor and volatile extractant from the drying oven 21 to prevent the extractant from evaporating heat and causing water vapor to condense and drip onto the membrane surface, thus completely eliminating the generation of water stain defects. The diaphragm 5 is suspended and transported in the drying chamber 21 by being clamped on the sides by axle pins and chain clamps 200, avoiding scratches and uneven drying caused by equipment contact; the heating devices 19 (such as far-infrared heating tubes) above and below the drying chamber 21 provide bidirectional full-coverage heat radiation to the suspended diaphragm; the dehumidification device 22 can be a rotary dehumidifier, which is an adsorption-type dry dehumidification device. The internal honeycomb moisture-absorbing rotary wheel rotates continuously, and adsorption dehumidification is completed in the treatment zone and regeneration zone. The heat regeneration treatment zone adsorbs air, and after adsorption saturation, it enters the regeneration zone, where the moisture is desorbed and discharged.

[0040] (5) Full process monitoring: The wind pressure, temperature and humidity in the small drying room, pre-drying chamber and drying room are monitored in real time by wind pressure meter 15 and temperature and humidity meter 14; the wind speed and wind direction at the film passage of the drying room are monitored in real time by anemometer 17 and wind direction meter 18; detection instruments are arranged at multiple locations in small drying room 6, drying room 21 and drying room film passage to realize real-time visual monitoring of wind field, temperature and humidity, wind speed and wind direction, to ensure the stable operation of each process parameter and provide data support for process optimization.

[0041] (6) Overall Synergistic Effect: Through the synergy of the extraction overflow system and the multi-stage spray purification equipment, the uniformity and cleanliness of the liquid on the surface of the separator 5 in the extraction section are significantly improved; through the synergy of the gradient pre-drying equipment and the suspended drying device, the uniformity and efficiency of the separator drying are both improved; the rotary dehumidifier prevents the generation of moisture on the separator surface from the source, and the wind pressure / temperature and humidity detection system enables the control of process parameters throughout the entire process. The cooperation of each system / equipment ultimately achieves a significant reduction in water stain defects in the lithium battery separator, and significantly improves the microstructure consistency, pore size uniformity and overall quality of the separator product.

[0042] Photographs of the diaphragm used in the production of this invention are shown below. Figure 5 As shown, by Figure 5 The reflective area shows no residual water stains on the diaphragm surface. Figure 6Electron micrographs also show that the membrane surface is free of water stains. The number of water-stain-free membranes produced using this invention compared to those produced by existing technologies is as follows: Figure 7 As shown, a comparison of the number of water stain defects in the diaphragm of the prior art and the present invention is presented in Tables 1 and 2.

[0043] Tables 1 to 2 and Figure 7 The results show that, under stable production conditions and consistent parameter settings, comparing the number of water stain defects in products using this device and those not using this device, it is clear that using this invention: 1. significantly reduces the number of water stain defects on the membrane roll surface, with the range reduced by 87% and the mean reduced by nearly 100%; 2. significantly increases the proportion of membrane rolls without water stain defects in the product (0%-88.33%).

[0044] Table 1 Comparison of the number of water stain defects in diaphragm samples of prior art and the present invention

[0045] Table 2 Comparison of the number of diaphragm rolls exhibiting water stain defects in prior art and the present invention

[0046] Table 1 shows the test method for the number of water stain defects in the diaphragm samples: Take 5 rolls of diaphragm with a winding length of 4500m each time, pull the starting end of the membrane roll open by more than 1m, apply slight force, flatten the diaphragm, visually confirm the membrane surface condition under bright light, record the number of water stain defects, check a total of 5 meters and 5 rolls, and analyze the maximum value, minimum value, range (difference between the maximum value and the minimum value) and average value.

Claims

1. A lithium battery separator extraction and drying apparatus, comprising an extraction device, characterized in that: Along the diaphragm transmission direction, the extraction device is followed in sequence by a spray purification device, a gradient pre-drying device, and a suspension drying device, wherein, The spray purification equipment includes a small drying chamber, which is equipped with a traction guide roller that moves the diaphragm laterally. Spray devices are installed above and below the diaphragm, and scraping devices are installed on the upper and lower sides of the diaphragm. A vacuum suction roller is installed after the last traction guide roller. When the diaphragm passes through the vacuum suction roller, the liquid on the diaphragm is absorbed. The gradient drying equipment includes a pre-drying chamber located after the vacuum suction roller and pre-drying rollers arranged vertically within the drying chamber. The pre-drying rollers are spaced vertically within the pre-drying chamber. The temperature of the pre-drying rollers increases gradually along the direction of the diaphragm's movement. Air knives are provided on both sides of the diaphragm, and an exhaust zone is provided on the wall of the pre-drying chamber. The suspended drying equipment includes a drying chamber, a drying chamber traction roller and a clamping mechanism for clamping both sides of the diaphragm, which are installed inside the drying chamber. The diaphragm moves laterally parallel to the horizontal plane inside the drying chamber under the guidance of the drying chamber traction roller. Heating devices for heating the diaphragm are respectively provided on the upper and lower sides of the diaphragm inside the drying chamber. A dehumidification device is also provided inside the drying chamber.

2. The lithium battery separator extraction and drying apparatus according to claim 1, characterized in that: The extraction device includes extraction tanks arranged in series. Each adjacent extraction tank has a membrane outlet and an overflow outlet. The overflow direction of the overflow outlet is opposite to the diaphragm running direction, and the height of the overflow outlet gradually increases along the diaphragm running direction. The liquid height in the extraction tank changes synchronously with the overflow outlet height, and the extractant overflows in the extraction tank in a counter-gradient manner. The bottom of the small drying chamber is connected to the final extraction tank by a liquid delivery pipeline. The liquid delivery pipeline is equipped with a drain valve and a liquid inlet valve. A diaphragm pump and a filter device are installed between the drain valve and the liquid inlet valve.

3. The lithium battery separator extraction and drying apparatus according to claim 1, characterized in that: The lithium battery separator extraction and drying device also includes a wind pressure / temperature and humidity detection component, specifically: a wind pressure meter and a temperature and humidity meter are installed above the spray device in the small drying chamber; a wind pressure meter and a temperature and humidity meter are installed above the uppermost pre-drying roller in the pre-drying chamber; a wind speed meter and a wind direction meter are installed above and below the membrane outlet of the drying chamber between the pre-drying chamber and the drying chamber; a wind pressure meter and a temperature and humidity meter are installed at the top of the drying chamber and near the membrane outlet.

4. The lithium battery separator extraction and drying apparatus according to claim 1, characterized in that: There are two or more traction guide rollers, each driven by an independent drive motor. On the diaphragm running path between the traction guide rollers, when the traction guide roller exits above the diaphragm, a spraying device and a scraping device are set above and below the diaphragm. When the traction guide roller exits below the diaphragm, a spraying device is set only below the diaphragm. The spraying device is located near the traction guide roller at the front end of the diaphragm running direction, and the spray nozzle of the spraying device extends more than 5 cm on each side of the diaphragm width.

5. The lithium battery separator extraction and drying apparatus according to claim 1, characterized in that: The small drying chamber and the pre-drying cavity are integrated into one unit, forming an L-shaped structure. The exhaust area is located on the upper side of the pre-drying area. The diaphragm is driven upward in the drying cavity. Pure water at 25-40℃ is introduced into the pre-drying roller, and the diaphragm is heated by heat transfer. The temperature difference between adjacent pre-drying rollers is 1-2℃.

6. The lithium battery separator extraction and drying apparatus according to claim 1, characterized in that: Each pre-drying roller is equipped with an air knife, and the number of air knives on both sides of the diaphragm is equal. The air knives are connected to a blower, a drying filter, and a high-pressure variable frequency air supply fan. The blower draws in outside air, which is heated and filtered by the drying filter, and then pressurized and delivered as clean air at 30-40°C by the high-pressure variable frequency air supply fan. The clean air is blown onto the diaphragm surface through the air knives. At least one high-pressure variable frequency air supply fan is provided, with a total rated air volume ≥3000m³ / h and an output air pressure controlled at 3000Pa~4000Pa. Angle adjustment devices are provided on both sides of the air knives to adjust the angle between the air knives and the diaphragm.

7. The lithium battery separator extraction and drying apparatus according to claim 1, characterized in that: The clamping mechanism includes a chain disc, a pivot pin, and a chain clamp. The chain disc drives the pivot pin and the chain clamp that clamps the sides of the diaphragm. The chain clamp is used to clamp the edges of both sides of the diaphragm. Four heating devices are arranged above and below the drying chamber, and the length of each heating device completely covers the width of the diaphragm. The dehumidification device is a rotary dehumidification device.

8. A lithium battery separator extraction and drying method, which is carried out using the lithium battery separator extraction and drying apparatus according to any one of claims 1-7, characterized in that, It includes the following steps: (1) Extraction overflow process: The diaphragm is extracted by the extractant in the extraction tank of the extraction device; (2) Spray purification process: The extracted diaphragm enters the small drying room, and the membrane surface carries a large amount of extractant. After the smooth and matte surfaces of the diaphragm are sprayed by the spray device, the liquid on the surface of the diaphragm is scraped off by the scraping device. The vacuum suction roller is vacuumed by the blower to adsorb the liquid on the surface of the diaphragm; (3) Gradient pre-drying process: The diaphragm carrying high-purity uniform extractant enters the pre-drying chamber and contacts the pre-drying roller. The extractant in the diaphragm is initially volatilized through heat transfer, and the pre-drying process is completed. The temperature of the drying roller increases in a gradient along the direction of the diaphragm running to ensure uniform volatilization of the extractant; at the same time, the air knife blows clean air that has been purified and heated to both sides of the diaphragm to achieve uniform pre-drying of the extractant remaining on the membrane surface; (4) Suspension drying process: the pre-dried diaphragm is pulled to the clamping mechanism by the drying oven traction roller, and the diaphragm is suspended and transported by clamping the sides of the diaphragm through the clamping mechanism. The heating devices above and below the diaphragm provide bidirectional full-coverage heating for the suspended diaphragm to achieve uniform and complete drying of the extractant remaining on the membrane surface; at the same time, the dehumidification device extracts water vapor and volatilized extractant from the drying oven.

9. The lithium battery separator extraction and drying method according to claim 8, characterized in that: In step (1), the overflow direction of the extractant is opposite to the running direction of the diaphragm. The new extractant is injected from the last stage extraction tank 1 and overflows in reverse through the overflow port with a height gradient along the running direction. In step (2), the extraction waste liquid accumulated at the bottom of the small drying room is extracted by the diaphragm pump, filtered to remove impurities, and then returned to the extraction tank for recycling.

10. The lithium battery separator extraction and drying method according to claim 8, characterized in that: In step (3), after the airflow blown by the air knife onto the diaphragm is pre-dried, it enters the exhaust zone in the opposite direction of the diaphragm's operation and is finally discharged from the pre-drying chamber through the exhaust pipe. And / or, real-time monitoring of air pressure, temperature and humidity in the small drying room, pre-drying chamber and drying room is conducted using an anemometer and a temperature and humidity meter; real-time monitoring of air speed and direction at the film outlet of the drying room is conducted using an anemometer and a wind direction meter.

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