Preparation device of sodium-ion battery diaphragm

Abstract

The utility model provides a preparation device of a sodium ion battery diaphragm, the preparation device comprises an extrusion mechanism, a casting cooling mechanism, a heat treatment mechanism, a clamping mechanism and a winding mechanism, the clamping mechanism is used for clamping and fixing a prefabricated film in the transverse direction and pulling and stretching the prefabricated film in the longitudinal direction to form the diaphragm, and the winding mechanism is used for winding and forming the diaphragm. Casting, heat treatment, stretching and rolling are integrated equipment, so that the production efficiency is improved; the winding mechanism is arranged after the heat treatment procedure, and different from the existing multiple winding and unwinding procedures, the contact between the diaphragm and the winding and unwinding roller can be reduced, the surface quality of the diaphragm is improved, the production process is simplified, and the production efficiency is improved. The clamping mechanism is arranged between the winding mechanism and the heat treatment mechanism, so that the prefabricated membrane can be transversely fixed, transverse necking is reduced, and the ventilation consistency and transverse strength of the membrane are improved. The clamping mechanism draws and stretches the prefabricated film in the longitudinal direction to form the diaphragm, the contact opportunity of the diaphragm and the roller surface is reduced, and the surface quality of the diaphragm is improved.

Description

Technical Field

[0001] The present application relates to the technical field of diaphragm preparation, and more specifically to a preparation device for a sodium ion battery diaphragm. Background Art

[0002] At present, in the process of producing diaphragms by dry unidirectional stretching in China, the production is carried out in the form of casting-heat treatment-compounding-stretching. When producing diaphragms, polyolefin raw materials are heated and melted, extruded from a specific mold and cooled to form a base film roll. The rolled base film is subjected to oven heat treatment to complete annealing and recrystallization. After annealing, the base film is unrolled, unidirectionally stretched to form holes and rolled to complete the preparation of unidirectional stretched lithium battery diaphragms. During the stretching process, the film is pulled by a steel roller, and the upper and lower surfaces directly contact the roller surface, resulting in problems such as dirty film surface, unqualified physical and chemical properties of the surface layer, and high scrap rate; at the same time, the diaphragm has transverse necking during unidirectional stretching, resulting in poor transverse air permeability consistency of the diaphragm and low transverse strength; the surface and inner layers of the film are subjected to different temperatures during stretching, resulting in problems such as difficult process adjustment, large physical and chemical differences between multi-layer films, and inability to fully cover physical and chemical monitoring; the entire production process involves multiple unwinding and unwinding, resulting in low production efficiency, low utilization rate, and high cost waste. Summary of the invention

[0003] The present application provides a sodium ion battery separator preparation device, which can improve processing stability, optimize product quality, achieve high production efficiency and high raw material utilization, and achieve the purpose of improving efficiency and reducing costs.

[0004] The present application provides a sodium ion battery separator preparation device, comprising:

[0005] An extrusion mechanism, the extrusion mechanism comprising an extrusion die head, the extrusion mechanism is used to melt the material for preparing the diaphragm, and extrude the material through the extrusion die head to obtain a sheet-like base film;

[0006] A casting cooling mechanism, wherein the casting cooling mechanism is used to cool the sheet-like base film extruded by the extrusion die head to form a casting film;

[0007] A heat treatment mechanism, the heat treatment mechanism is used to anneal and recrystallize the cast film to form a pre-film;

[0008] A clamping mechanism, the clamping mechanism is used to fix the prefabricated membrane in the transverse direction and to pull and stretch the prefabricated membrane in the longitudinal direction to form a diaphragm;

[0009] and a winding mechanism, the winding mechanism being used to roll the diaphragm into shape;

[0010] Furthermore, the extrusion mechanism, the casting cooling mechanism, the heat treatment mechanism, the clamping mechanism and the winding mechanism are sequentially arranged along the membrane production process.

[0011] In an optional embodiment, it also includes a heat preservation mechanism, which includes a heat preservation box. The heat preservation box is arranged on a side of the heat treatment mechanism away from the casting cooling mechanism. The prefabricated film enters the heat preservation box after annealing treatment, and the winding mechanism pulls the prefabricated film to stretch it in a direction away from the heat treatment mechanism.

[0012] In an optional embodiment, the heat preservation box has a low temperature zone, a high temperature zone and a shaping zone, and the low temperature zone, the high temperature zone and the shaping zone are arranged in sequence along the direction from the heat treatment mechanism to the winding mechanism.

[0013] In an optional embodiment, the temperature of the low temperature zone is 40°C-80°C; the temperature of the high temperature zone is 100°C-160°C; and the temperature of the shaping zone is 100°C-200°C.

[0014] In an optional embodiment, the clamping mechanism includes a clamping assembly, which can clamp or release the diaphragm, and the clamping assembly includes a first clamping part, a second clamping part and a clamping drive assembly, a gap is provided between the first clamping part and the second clamping part for placing the prefabricated film, and the clamping drive assembly is used to drive the first clamping part and the second clamping part to move closer to or away from each other, so as to clamp or release the prefabricated film.

[0015] In an optional embodiment, the mechanism also includes a fixed base and a support frame, the clamping assembly is arranged on the support frame, and the support frame is movably arranged on the fixed base, and the support frame can move along the longitudinal direction on the fixed base and drive the clamping assembly to move along the longitudinal direction to pull and stretch the prefabricated membrane along the longitudinal direction to form the diaphragm.

[0016] In an optional embodiment, the heat treatment mechanism includes a heat treatment heating component, a heat treatment insulation box, and a guide roller. The heat treatment insulation box has a heat treatment chamber for annealing and recrystallizing the cast film to form a prefabricated film. The heat treatment heating component is used to heat the heat treatment chamber to reach a preset heat treatment temperature. The guide roller is arranged in the heat treatment chamber to guide the cast film.

[0017] In an optional embodiment, the heat treatment chamber includes a first end and a second end, both of which have openings to connect the heat treatment chamber with the outside, and the first end and the second end are arranged sequentially along the longitudinal direction of the prefabricated film, and the guide roller can guide the cast film to enter the heat treatment chamber from the first end and exit through the second end.

[0018] In an optional embodiment, the guide roller is provided in plurality, the axes of the plurality of guide rollers are parallel, and the axes of the guide rollers are perpendicular to a line connecting the midpoints of the first end and the second end.

[0019] In an optional embodiment, the casting cooling mechanism includes a casting cooling roller, which can cool the sheet base film into the casting film; the winding mechanism includes a winding roller, and the axes of the winding roller, the casting cooling roller and the guide roller are parallel.

[0020] According to the preparation device of the sodium ion battery diaphragm in the above embodiment, the casting, heat treatment, stretching and winding are set as an integrated device. Through the setting of the winding mechanism, the diaphragm can be rolled and formed, and the prefabricated film after heat treatment can be stretched to form it into a diaphragm, which simplifies the entire diaphragm production process and equipment and improves the production efficiency; at the same time, different from the existing multiple winding and unwinding processes, it can reduce the contact between the diaphragm and the winding and unwinding rollers, and improve the surface quality of the diaphragm. Through the setting of the clamping mechanism, the prefabricated film is transversely fixed and longitudinally pulled and stretched after heat treatment, so that the diaphragm does not need to contact the roller surface, reducing the physical and chemical unqualifiedness of the two surfaces of the diaphragm due to the temperature difference. At the same time, since the diaphragm does not contact the roller surface, the damage to the diaphragm surface is reduced, and the utilization rate of the diaphragm is improved. Since the clamping mechanism can fix the diaphragm in the transverse direction, the transverse necking is reduced when the diaphragm is stretched, and the air permeability consistency and transverse strength of the diaphragm are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a preparation device for a sodium ion battery separator in one embodiment;

[0022] Figure 2 Schematic diagram of the structure of a clamping assembly in one embodiment.

[0023] Among them: 100, extrusion mechanism; 110, extrusion die; 200, casting cooling mechanism; 210, casting cooling roller; 300, heat treatment mechanism; 310, heat treatment insulation box; 311, heat treatment chamber; 3111, first end; 3112, second end; 320, guide roller; 400, clamping mechanism; 410, clamping assembly; 411, first clamping part; 412, second clamping part; 420, fixed base; 430, support frame; 500, winding mechanism; 510, winding roller; 600, insulation mechanism; 610, insulation box; 611, low temperature zone; 612, high temperature zone; 613, shaping zone. DETAILED DESCRIPTION

[0024] The present application is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present application to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, and methods. In some cases, some operations related to the present application are not shown or described in the specification, in order to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0025] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations, and the operation steps involved in each embodiment can also be replaced or adjusted in a sequence in a manner that is obvious to those skilled in the art. Therefore, the specification and drawings are only for the purpose of clearly describing a certain embodiment and do not mean that the composition and / or sequence are necessary.

[0026] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0027] refer to Figure 1-2The present application provides a sodium ion battery diaphragm preparation device, which can improve processing stability, optimize product quality, achieve high production efficiency and high raw material utilization, and achieve the purpose of improving efficiency and reducing costs. It includes an extrusion mechanism 100, a casting cooling mechanism 200, a heat treatment mechanism 300, a clamping mechanism 400 and a winding mechanism 500, and the extrusion mechanism 100, the casting cooling mechanism 200, the heat treatment mechanism 300, the clamping mechanism 400 and the winding mechanism 500 are arranged in sequence along the diaphragm production process. The extrusion mechanism 100 includes an extrusion die 110, and the extrusion mechanism 100 is used to melt the material for preparing the diaphragm, and extrude it through the extrusion die 110 to obtain a sheet-like base film, the cast cooling mechanism 200 is used to cool the sheet-like base film extruded by the extrusion die 110 to form a cast film, the heat treatment mechanism 300 is used to anneal and recrystallize the cast film to form a pre-film, the clamping mechanism 400 can fix the pre-film in the horizontal direction, and pull and stretch the pre-film in the longitudinal direction to stretch it into holes to form a diaphragm that meets the requirements, and the winding mechanism 500 can roll the diaphragm into shape. The clamping mechanism 400 and the winding mechanism 500 cooperate with each other, which not only realizes the fixation of the pre-film during the stretching process, but also reduces the existing winding and unwinding structure and process between the two processes, thereby improving the surface quality of the diaphragm and the efficiency of diaphragm preparation.

[0028] It should be further explained that the longitudinal direction mentioned in this article is the direction in which each small segment of the prefabricated membrane moves, and the direction perpendicular to the longitudinal direction within the prefabricated membrane surface is the transverse direction. Figure 2 The direction indicated by the arrow in the figure is the longitudinal direction of the prefabricated membrane, and correspondingly, the direction perpendicular to it is the transverse direction of the prefabricated membrane.

[0029] The present application integrates casting, heat treatment, stretching and winding, which is different from the existing process. A winding and unwinding structure is set between each process. The winding and unwinding structure generally includes a winding roller and an unwinding roller. The roller surface is smooth, but the roller surface is inevitably contaminated with debris or slightly worn due to use during the production process. The present application only sets a winding mechanism 500 at the end of the process, reducing the setting of the winding and unwinding structure, so that the diaphragm (sheet base film, cast film and prefabricated film, etc.) passes through the extrusion mechanism 100, the casting cooling mechanism 200, the heat treatment mechanism 300, the clamping mechanism 400 and the winding mechanism 500 continuously (without passing through an additional winding and unwinding mechanism), reducing the number of times the diaphragm surface contacts the roller surface during the diaphragm preparation process, thereby avoiding damage to the diaphragm surface by the roller surface, improving the surface quality of the diaphragm, and thus improving the utilization rate of the two surfaces of the diaphragm. At the same time, the reduction of production processes can also improve the preparation efficiency of the diaphragm and reduce production costs.

[0030] On the other hand, since the roller surface is generally made of metal material (of course, it can also be made of other materials, such as polymer materials), one surface of the diaphragm is in contact with the roller surface when winding and unwinding, and the other surface is in contact with the air, which leads to inconsistent temperatures on the two surfaces of the diaphragm, resulting in physical and chemical differences between the two surfaces. The present application reduces the contact between the roller surface and the diaphragm surface, which can reduce such physical and chemical differences, thereby improving the quality of the diaphragm and increasing the utilization rate of the diaphragm.

[0031] Since the diaphragm will shrink in the lateral direction during the stretching process, the clamping mechanism 400 is symmetrically arranged on both sides of the prefabricated membrane in the lateral direction, which can fix the prefabricated membrane in the lateral direction and reduce its necking deformation in the lateral direction when the prefabricated membrane is pulled and stretched, thereby improving the overall air permeability consistency and lateral strength of the final formed diaphragm.

[0032] When the diaphragm is stretched, a single-layer prefabricated film that has been cast and heat-treated in sequence is stretched. If the diaphragm needs to be composited later, single-layer stretching makes it easy to adjust the process in time according to the diaphragm performance, which can reduce the physical and chemical differences between multi-layer films and ultimately improve product performance.

[0033] The core process of diaphragm preparation is micropore preparation, which is completed through a stretching process, generally including dry stretching and wet stretching, and dry stretching includes dry unidirectional stretching and dry bidirectional stretching. The present application uses a winding mechanism 500 as an integrated device for stretching and winding, and adopts dry unidirectional stretching, which generally includes cold stretching, hot stretching and heat setting processes. That is, first stretching is performed at a low temperature to form micro defects such as silver streaks (cold stretching), and then the defects are pulled apart at a high temperature (hot stretching) to form micropores, and finally heat-set to form a diaphragm that meets the requirements.

[0034] During the stretching process, a heat preservation mechanism 600 is also included, which is used to create environmental conditions for the prefabricated film to be stretched into a diaphragm. The heat preservation mechanism 600 includes a heat preservation box 610, which is arranged on the side of the heat treatment mechanism 300 away from the casting cooling mechanism 200. The prefabricated film enters the heat preservation box 610 after annealing treatment, and the winding mechanism 500 pulls the prefabricated film to stretch in a direction away from the heat treatment mechanism 300.

[0035] Furthermore, the heat preservation box 610 has a low temperature zone 611, a high temperature zone 612 and a shaping zone 613, and the low temperature zone 611, the high temperature zone 612 and the shaping zone 613 are sequentially arranged and continuously arranged along the direction from the heat treatment mechanism 300 to the winding mechanism 500.

[0036] Furthermore, the temperature of the low temperature zone 611 is 40°C-80°C, and the low temperature zone 611 is used for cold stretching; the temperature of the high temperature zone 612 is 100°C-160°C, and the high temperature zone 612 is used for hot stretching; the temperature of the shaping zone 613 is 100°C-200°C, which is used to achieve thermal shaping of the micropores of the diaphragm.

[0037] The clamping mechanism 400 is arranged on one side of the heat treatment mechanism 300 close to the winding mechanism 500, and the clamping mechanism 400 includes a clamping assembly 410, and the clamping assembly 410 can clamp or release the diaphragm. The clamping assembly 410 includes a first clamping part 411, a second clamping part 412 and a clamping drive assembly (not shown in the figure), and a gap is provided between the first clamping part 411 and the second clamping part 412 for placing the prefabricated film, and the clamping drive assembly is used to drive the first clamping part 411 and the second clamping part 412 to move closer to or away from each other, so as to clamp or release the prefabricated film.

[0038] In the process of preparing the diaphragm, the prefabricated film undergoes lateral necking during the stretching process. When the prefabricated film passes the position of the clamping mechanism 400, the first clamping portion 411 and the second clamping portion 412 are driven to approach each other by the clamping drive assembly, so that the two cooperate to clamp the prefabricated film, and the clamping assembly 410 is evenly arranged on both sides of the prefabricated film in the transverse direction to clamp and fix the prefabricated film, which can fix the prefabricated film to prevent it from shrinking in the transverse direction, thereby preventing it from undergoing lateral necking.

[0039] Specifically, the clamping drive assembly provides a driving force to make the first clamping part 411 and the second clamping part 412 move linearly. The clamping drive assembly can be a cylinder or a linear motor, or can be a combination of a rotary motor and a connecting rod mechanism or a gear rack structure, which converts the rotary motion of the rotary motor into a linear motion, so that the first clamping part 411 and the second clamping part 412 move linearly.

[0040] In one embodiment, the clamping mechanism 400 also includes a fixed base 420 and a support frame 430, the clamping assembly 410 is arranged on the support frame 430, and multiple clamping assemblies 410 are supported and fixed by the support frame 430, the support frame 430 is movably arranged on the fixed base 420, and the fixed base 420 extends in the longitudinal direction. The support frame 430 can slide (move or move) relatively in the longitudinal direction on the fixed base 420, and drive the clamping assembly 410 to move synchronously in the longitudinal direction, so that the prefabricated membrane can be pulled and stretched along the longitudinal direction to form the diaphragm.

[0041] The clamping mechanism 400 also includes a longitudinal drive assembly (not shown in the figure), which is connected to the support frame 430 and is used to drive the support frame 430 to move linearly in the longitudinal direction, thereby driving the clamping assembly 410 to move linearly in the longitudinal direction. Since the clamping assembly 410 clamps the prefabricated membrane, during its movement, it can also drive the prefabricated membrane to be synchronously pulled and stretched in the longitudinal direction, thereby completing microporous molding and preparing a diaphragm.

[0042] The longitudinal drive assembly may be a cylinder or a linear motor, or may be a combination of a rotary motor and a connecting rod mechanism or a rack and pinion structure, which converts the rotary motion of the rotary motor into a linear motion, so that the first support frame 430 performs a linear motion.

[0043] Furthermore, the clamping assemblies 410 are provided with six and are symmetrically arranged along the longitudinal center line of the prefabricated film, so that the prefabricated film is stretched uniformly during the stretching process, thereby improving the uniformity and consistency of the performance of the prepared diaphragm. Of course, in other embodiments, the number of the clamping assemblies 410 can be adjusted according to the designed distance between the heat treatment mechanism 300 and the winding mechanism 500.

[0044] Furthermore, since the clamping assembly 410 is arranged on both lateral sides of the prefabricated membrane and is laterally fixed during the stretching process, at least part of the clamping assembly 410 may be in contact with the insulation mechanism 600, that is, there is a possibility of being in a high temperature environment. Therefore, the clamping assembly 410 has a certain high temperature resistance.

[0045] The heat treatment mechanism 300 includes a heat treatment heating component (not shown in the figure), a heat treatment insulation box 310, and a guide roller 320. The heat treatment insulation box 310 has a heat treatment chamber 311 for annealing and recrystallizing the cast film to form a prefabricated film. The heat treatment heating component is used to heat the heat treatment chamber 311 to reach a preset heat treatment temperature; the guide roller 320 is arranged in the heat treatment chamber 311 to guide the cast film.

[0046] The heat treatment chamber 311 includes a first end 3111 and a second end 3112, and the first end 3111 and the second end 3112 both have openings to connect the heat treatment chamber 311 with the outside, and the first end 3111 and the second end 3112 are arranged in sequence along the longitudinal direction of the prefabricated film, and the guide roller 320 can guide the cast film to enter the heat treatment chamber 311 from the first end 3111 and exit through the second end 3112.

[0047] Furthermore, the guide rollers 320 are provided in plurality, the axes of the plurality of guide rollers 320 are parallel, and the axes of the guide rollers 320 are perpendicular to a line connecting the midpoints of the first end 3111 and the second end 3112 .

[0048] The casting cooling mechanism 200 includes a casting cooling roller 210, and the casting cooling roller 210 can cool the sheet base film to form the casting film; the winding mechanism 500 includes a winding roller 510, and the axes of the winding roller 510 and the casting cooling roller 210 and the guide roller 320 are parallel.

[0049] Furthermore, the casting cooling roller 210 is made of metal material, which can take away the temperature of the sheet-like base film, thereby cooling it down and solidifying it into a casting film.

[0050] In other embodiments, the casting cooling roller 210 is a hollow roller structure with a cooling device inside. The cooling device removes the temperature of the sheet base film on the surface of the casting cooling roller 210 by water cooling or air cooling, thereby cooling it and solidifying it into a casting film.

[0051] The working process of preparing the diaphragm in the present application is: the raw materials for preparing the diaphragm (such as polyolefin) are placed in the extrusion mechanism 100 according to the ratio, the extrusion mechanism 100 plasticizes and melts the solid material into a melt with uniform temperature and extrude it continuously, and the extruded melt is defined as a sheet-like base film. After the sheet-like base film is cooled into a cast film by the cast cooling roller 210 of the cast cooling mechanism 200, it is annealed and recrystallized by the heat treatment mechanism 300 to form a prefabricated film, and then the prefabricated film is stretched and rolled into one piece by the winding mechanism 500 to form a plurality of micropores on the prefabricated film, thereby preparing a rolled diaphragm for use in subsequent processes.

[0052] It should be noted that the above-mentioned diaphragm is used in the field of batteries, and the battery may include a sodium ion battery or a lithium ion battery. Optionally, the present application is mainly used for the preparation of sodium ion battery diaphragms.

[0053] The advantages of the diaphragm prepared in the present application are explained below with specific examples.

[0054] Embodiment 1

[0055] refer to Figure 1 and Figure 2This embodiment adopts the sodium ion battery separator preparation device provided in the present application, and adopts a single-layer separator prepared by an integrated device of casting, heat treatment, stretching and winding processes. Specifically, the casting speed of the casting cooling mechanism 200 is 80m / min, the temperature in the heat treatment chamber 311 of the heat treatment mechanism 300 is 140°C, and the moving speed in the heat treatment chamber 311 is 2m / min. When the clamping mechanism 400 performs stretching, the prefabricated film is cold stretched, hot stretched and heat set in sequence, and all of them are performed in the insulation box 610. The temperature of the low temperature zone 611 in the insulation box 610 is 60°C, that is, the temperature during cold stretching is 60°C, and the cold stretching speed ratio is 1.2. The temperature of the high temperature zone 612 in the insulation box 610 is 140°C, that is, the temperature during hot stretching is 140°C, and the speed ratio of hot stretching is 1.8. The temperature of the heat setting zone 613 is 150°C, that is, the temperature during heat setting is 150°C, and the speed ratio of heat setting is 0.8. The total speed ratio in the stretching process is 2.1.

[0056] Comparative Example 1

[0057] This comparative example uses a device that integrates the casting and compounding processes and the heat treatment and stretching processes to prepare the diaphragm. First, the casting-compounding device is used to prepare the cast film, and then the multi-layer cast film is unwound, compounded, and wound to prepare the composite film. The composite film is then annealed and stretched into holes by a heat treatment and stretching device, that is, the multi-layer film body is first compounded to form a multi-layer film, and then the subsequent heat treatment and stretching process are carried out. After the multi-layer diaphragm is stretched, the single layer is peeled off to obtain a single-layer porous diaphragm that can be put into use. Specifically, the casting speed of the casting-composite integrated equipment is 80m / min, the temperature of the heat treatment of the integrated equipment with heat treatment and stretching processes is 140°C, the moving speed during heat treatment is 2m / min, and during stretching, the steel roller pulls the prefabricated film to perform cold stretching, hot stretching and heat setting in sequence. The temperature during cold stretching is 60°C, and the cold stretching speed ratio is 1.2. The temperature during hot stretching is 140°C, and the speed ratio of hot stretching is 1.8. The temperature during heat setting is 150°C, and the speed ratio of heat setting is 0.8. The total speed ratio in the stretching process is 2.1.

[0058] Comparative Example 2

[0059] This comparative example adopts a split-type device for casting-heat treatment-compounding-stretching to prepare a diaphragm. A plurality of independent split-type devices are used to independently carry out casting, heat treatment, compounding, and stretching processes in sequence. There are winding structures and unwinding structures between the multiple processes, that is, winding structures and unwinding structures are set between each independent casting device, heat treatment device, compounding device, stretching device, etc. First, a cast film is prepared, and after being wound up by the winding structure, it is unwound to the heat treatment device through the unwinding structure to obtain a prefabricated film after annealing and heat treatment. After the prefabricated film is wound up, it is unwound, compounded, and wound up to prepare a composite film. The composite film is then unwound to the stretching device for stretching process to form holes, and finally the composite porous film is peeled off to form a single-layer porous diaphragm. Specifically, the casting speed is 80m / min, the temperature during heat treatment is 140°C, and during stretching, the steel roller pulls the prefabricated film to perform cold stretching, hot stretching and heat setting in sequence. The temperature during cold stretching is 60°C, and the cold stretching speed ratio is 1.2. The temperature during hot stretching is 140°C, and the speed ratio of hot stretching is 1.8. The temperature during heat setting is 150°C, and the speed ratio of heat setting is 0.8. The total speed ratio in the stretching process is 2.1.

[0060] The performance tests of the diaphragms prepared in Example 1, Comparative Example 1 and Comparative Example 2 were carried out, and the thickness of the stretched film (μm), the surface density (g / m 2 ), porosity (%), flat head puncture strength (gf), air permeability / extreme difference (s / 100ml), MD tensile strength (kgf / cm 2 ), TD tensile strength (kgf / cm 2 ), MD elongation at break (%), TD elongation at break (%), MD elastic modulus, TD elastic modulus, MD thermal shrinkage (130℃ / 0.5h), foreign matter on the membrane surface (particle size 20μm-50μm) and other dimensions were tested.

[0061] The thickness is obtained by measuring the prepared diaphragm using a thickness gauge.

[0062] The porosity and surface density are measured by the following method: samples of the same area are cut from the diaphragm TD at a certain interval and then weighed on a balance to obtain the results.

[0063] The puncture strength is measured by the following method: cutting along the diaphragm TD at a certain interval, with a puncture needle diameter of 1 mm, and recording the maximum puncture force when the probe punctures the membrane, which is the puncture strength.

[0064] The air permeability value is measured by the following method: the air permeability value is measured using an air permeability analyzer, and the time required for a certain amount of air (100 ml) to pass through a diaphragm of a specified area under a constant pressure is recorded, which is the air permeability value (s / 100 ml).

[0065] The tensile strength, elongation at break and elastic modulus are measured by the following method: cutting specimens along the TD and MD of the diaphragm, marking the initial length, and recording the value of the sample when the testing machine stops.

[0066] The thermal shrinkage is measured by the following method: the diaphragm is clamped and placed in an oven for baking, and the changes in length and width before and after baking are calculated as the thermal shrinkage value.

[0067] The foreign matter on the membrane surface is determined by the following method: using 3M glue to take samples on the membrane surface and then testing it using a cleanliness analyzer.

[0068] It should be further explained that MD mentioned in this article is the abbreviation of Machine Direction, which means the machine direction, that is, the longitudinal direction. TD is the abbreviation of Transverse Direction, which means perpendicular to the machine direction, that is, the transverse direction.

[0069] The specific test results are shown in Table 1 below.

[0070] Table 1

[0071]

[0072]

[0073] The above results show that the diaphragm prepared by Example 1 using a lithium battery diaphragm device with integrated casting, heat treatment, stretching and winding processes has no significant difference in MD direction physical and chemical properties from Comparative Examples 1 and 2, but the performance in TD direction is significantly improved. Due to the fixation of the clamping assembly 410 in the TD direction, the degree of necking can be reduced, the TD direction physical and chemical consistency is better, and the air permeability value extreme difference is significantly reduced. The data on foreign matter on the membrane surface show that the foreign matter on the surface of the diaphragm prepared in Example 1 is significantly reduced.

[0074] In Comparative Example 1, a winding structure and an unwinding structure need to be set between the casting-compounding process and the heat treatment-stretching process, and a winding structure also needs to be set after stretching for winding and molding. In Comparative Example 2, all processes are set independently, that is, a winding structure and an unwinding structure need to be set between casting, compounding, heat treatment, and stretching. The present application only sets a winding structure after the heat treatment mechanism, and uses the winding structure to achieve stretching and winding. No winding structure and unwinding structure are set between other processes. There is no need for multiple winding and unwinding in the entire preparation process. Judging from the detection results of foreign matter on the membrane surface, the foreign matter on the membrane surface of the present application is significantly reduced, which can effectively improve the surface quality of the membrane.

[0075] This application does not contain composite equipment, and a single-layer diaphragm is prepared by an equipment that integrates the processes of casting, heat treatment, stretching and winding. Compared with the traditional device and method in Comparative Examples 1 and 2 (casting-heat treatment-compounding-stretching or casting-compounding-heat treatment-stretching), which first composites a multilayer film, stretches the multilayer film together, and then peels it into a single-layer diaphragm, it can be clearly seen from the extreme difference in air permeability, TD tensile strength and TD elongation at break in the above table that this application eliminates the need for composite equipment and uses integrated equipment throughout the process to prepare a single-layer diaphragm, which is convenient for process adjustment during the preparation process and can also avoid the existence of physical and chemical differences between multilayer films during the production of composite films.

[0076] The above specific examples are used to illustrate the present application, which is only used to help understand the present application and is not intended to limit the present application. For technicians in the technical field to which the present application belongs, they can also make some simple deductions, deformations or substitutions based on the ideas of the present application.

Claims

1. A preparation device for a sodium ion battery separator, characterized in that: include: An extrusion mechanism, the extrusion mechanism comprising an extrusion die head, the extrusion mechanism is used to melt the material for preparing the diaphragm, and extrude the material through the extrusion die head to obtain a sheet-like base film; A casting cooling mechanism, wherein the casting cooling mechanism is used to cool the sheet-like base film extruded by the extrusion die head to form a casting film; A heat treatment mechanism, the heat treatment mechanism is used to anneal and recrystallize the cast film to form a pre-film; A clamping mechanism, the clamping mechanism is used to fix the prefabricated membrane in the transverse direction and to pull and stretch the prefabricated membrane in the longitudinal direction to form a diaphragm; and a winding mechanism, the winding mechanism being used to roll the diaphragm into shape; Furthermore, the extrusion mechanism, the casting cooling mechanism, the heat treatment mechanism, the clamping mechanism and the winding mechanism are sequentially arranged along the membrane production process.

2. The preparation device for sodium ion battery separator according to claim 1, characterized in that: It also includes a heat preservation mechanism, which includes a heat preservation box. The heat preservation box is arranged on a side of the heat treatment mechanism away from the casting cooling mechanism. The prefabricated film enters the heat preservation box after annealing treatment, and the winding mechanism pulls the prefabricated film and stretches it in a direction away from the heat treatment mechanism.

3. The preparation device of the sodium ion battery separator according to claim 2, characterized in that: The heat preservation box has a low temperature zone, a high temperature zone and a shaping zone, and the low temperature zone, the high temperature zone and the shaping zone are arranged in sequence along the direction from the heat treatment mechanism to the winding mechanism.

4. The preparation device for sodium ion battery separator according to claim 3, characterized in that: The temperature of the low temperature zone is 40°C-80°C; the temperature of the high temperature zone is 100°C-160°C; the temperature of the shaping zone is 100°C-200°C.

5. The preparation device of the sodium ion battery separator according to claim 1, characterized in that: The clamping mechanism includes a clamping assembly, which can clamp or release the diaphragm. The clamping assembly includes a first clamping part, a second clamping part and a clamping drive assembly. A gap is provided between the first clamping part and the second clamping part for placing the prefabricated film. The clamping drive assembly is used to drive the first clamping part and the second clamping part to move closer to or away from each other to clamp or release the prefabricated film.

6. The device for preparing a sodium ion battery separator according to claim 5, characterized in that: The clamping mechanism also includes a fixed base and a support frame, the clamping assembly is arranged on the support frame, and the support frame is movably arranged on the fixed base. The support frame can move along the longitudinal direction on the fixed base and drive the clamping assembly to move along the longitudinal direction to pull and stretch the prefabricated membrane along the longitudinal direction to form the diaphragm.

7. The preparation device for sodium ion battery separator according to claim 1, characterized in that: The heat treatment mechanism includes a heat treatment heating component, a heat treatment insulation box, and a guide roller. The heat treatment insulation box has a heat treatment chamber for annealing and recrystallizing the cast film to form a prefabricated film. The heat treatment heating component is used to heat the heat treatment chamber to reach a preset heat treatment temperature. The guide roller is arranged in the heat treatment chamber to guide the cast film.

8. The device for preparing a sodium ion battery separator according to claim 7, characterized in that: The heat treatment chamber includes a first end and a second end, both of which have openings to connect the heat treatment chamber with the outside, and the first end and the second end are arranged in sequence along the longitudinal direction of the prefabricated film, and the guide roller can guide the cast film to enter the heat treatment chamber from the first end and exit through the second end.

9. The device for preparing a sodium ion battery separator according to claim 8, characterized in that: There are multiple guide rollers, the axes of the multiple guide rollers are parallel, and the axes of the guide rollers are perpendicular to the line connecting the midpoints of the first end and the second end.

10. The device for preparing a sodium ion battery separator according to claim 7, characterized in that: The casting cooling mechanism comprises a casting cooling roller, which can cool the sheet-like base film into the casting film; the winding mechanism comprises a winding roller, and the axes of the winding roller, the casting cooling roller and the guide roller are parallel.

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