Preparation method and preparation device for dry electrode sheet film

Abstract

A preparation method for a dry electrode sheet film and a preparation device for a dry electrode sheet film. The preparation method for a dry electrode sheet film comprises: providing a pair of first rollers (20) having a roller diameter of d1, setting the pressure of the first rollers (20) to be t1, and roll-pressing fibrillated powder by means of the pair of first rollers (20) to obtain a primary film (300) having a primary thickness; providing a pair of second rollers (40) having a roller diameter of d2, wherein d2<d1, setting the pressure of the second rollers (40) to be t2, wherein t2<t1, and performing primary thinning on the primary film (300) by means of the pair of second rollers (40) to obtain a secondary film (400) having a secondary thickness; and providing a pair of third rollers (50) having a roller diameter of d3, wherein d3>d1, setting the pressure of the third rollers (50) to be t3, wherein t3>t1, and performing secondary thinning on the secondary film (400) by means of the third rollers (50) to obtain a target film (500) having a target thickness.

Description

Preparation method and equipment of dry-process electrode membrane

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 15, 2024, with application number 2024100581145. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of electrode and pole piece technology, and in particular to a method and equipment for preparing a dry-process pole piece and membrane. Background Art

[0003] In the preparation process of lithium-ion batteries, in recent years, a dry process technology, which is different from wet battery manufacturing, has been widely used. Since dry electrode technology does not use or uses a small amount of solvent, it saves a lot of energy consumption and solvent recovery costs compared to the wet process. At the same time, it saves dozens of meters of baking channels and reduces investment costs, so it has cost advantages.

[0004] During the dry electrode preparation process, active materials, conductive agents, and binders are subjected to shear force at a specific temperature to fiberize the active materials, conductive agents, and binders to obtain fiberized powder. The powder is then rolled into a film and then rolled up. Existing membranes prepared using dry technology have insufficient membrane strength due to improper matching of roller size and pressure.

[0005] The present application aims to solve the following technical problem: in the existing membrane prepared by dry process technology, the membrane strength is insufficient due to improper matching of the pressing roller size and pressure. Technical Solutions

[0006] In a first aspect, the present application provides a method for preparing a dry-process electrode membrane, comprising:

[0007] Providing a pair of first rollers with a roller diameter of d1, setting the pressure of the first rollers to t1, and rolling the fiberized powder by the pair of first rollers to obtain an initial film sheet with an initial thickness;

[0008] providing a pair of second rollers with a roller diameter of d2, where d2 is less than d1, setting a pressure of the second rollers to t2, where t2 is less than t1, and performing a primary thinning on the primary film by the pair of second rollers to obtain a secondary film of secondary thickness;

[0009] At least one pair of third rollers with a roller diameter of d3 is provided, and d3>d1, the pressure of the third rollers is set to t3, and t3>t1, and the secondary membrane is thinned twice by the third rollers to obtain a target membrane with a target thickness.

[0010] In a second aspect, the present application provides a dry-process electrode membrane preparation device, comprising:

[0011] A pair of first rollers, disposed downstream of the material discharge structure, for rolling the fiberized powder to obtain an initial film sheet of initial thickness, wherein the diameter of the first rollers is d1 and the pressure of the first rollers is t1;

[0012] a pair of second rollers, disposed downstream of the pair of first rollers, for performing a primary thinning on the primary film to obtain a secondary film of secondary thickness; the diameter of the second rollers is d2, and the pressure of the second rollers is t2;

[0013] At least one pair of third rollers is provided downstream of the pair of second rollers for performing secondary thinning on the secondary film to obtain a target film of target thickness. The diameter of the third rollers is d3, and the pressure of the second rollers is t3.

[0014] Among them, d3>d1>d2, t3>t1>t2. Beneficial effects

[0015] By setting the roller diameters and pressures of the first roller for pressing the powder into a film and the second and third rollers for adjusting the thickness and compaction of the film once and twice to d3>d1>d2 and t3>t1>t2, when pressing the powder into a film and adjusting it, the powder can first be pressed into an initial film by the first roller with a larger roller diameter and pressure, and then the initial film can be quickly coarse-adjusted at a faster walking speed by the second roller with a smaller roller diameter and pressure, so that the thickness and compaction of the film are preliminarily adjusted, and finally the third roller with the largest roller diameter and maximum pressure is used to finely adjust the pressure of the film, so that the obtained film can meet the required thickness and have a higher compaction degree, and at the same time, the film has higher strength and more suitable toughness and other mechanical properties, and at the same time, the film has an excellent pore structure to improve the battery electrical performance when the film is used in a battery, and at the same time has lower tortuosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic flow chart of a method for preparing a dry-process electrode membrane according to an embodiment of the present application;

[0017] FIG2 is a schematic diagram showing a comparison of the tensile strength of a diaphragm prepared in an embodiment of the present application and a diaphragm prepared by a conventional process;

[0018] FIG3 is a schematic structural diagram of a dry-process electrode membrane preparation device according to an embodiment of the present application.

[0019] Figure: 200-Dry process electrode membrane preparation equipment, 10-feeding structure, 11-vibrating screen, 12-movable material trough, 20-first roller, 30-cutting structure, 31-support roller, 32-edge trimming knife, 33-powder suction nozzle, 34-dust removal box, 40-second roller, 41-first scraper, 42-first guide roller, 50-third roller, 51-second scraper, 60-second guide roller, 70-winding structure, 300-primary membrane; 400-secondary membrane, 500-target membrane. Modes for Carrying Out the Invention

[0020] In the description of this application, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting this application.

[0021] The present application will be further described in detail below with reference to the accompanying drawings.

[0022] Please refer to FIG1 , which shows a method 100 for preparing a dry-process electrode membrane according to an embodiment of the present application, comprising the following steps:

[0023] S1, the fiberized powder is discharged through the discharge structure 10.

[0024] The fiberized powder in this embodiment includes, but is not limited to, an active material, a conductive agent, and a binder, and is formed by applying shear force to the active material, the conductive agent, and the binder. The active material can be a positive electrode material such as lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium cobalt oxide, or one or more combinations of graphite and / or silicon oxygen / silicon carbon negative electrode materials; the conductive agent includes, but is not limited to, one or more combinations of conductive carbon black, carbon nanotubes, graphene, etc.; and the binder includes, but is not limited to, one or more combinations of polytetrafluoroethylene, tetrafluoroethylene, polyacrylic acid, carboxymethyl cellulose, polyethylene glycol, polyvinyl pyrrolidone, etc.

[0025] After shearing force is applied to the active material, the conductive agent and the binder to obtain fiberized powder, the powder is discharged through the discharge structure 10 .

[0026] Specifically, the material discharge structure 10 of this embodiment includes a vibrating screen 11 and a movable material trough 12 provided below the vibrating screen 11. The vibrating screen 11 includes two layers of screens arranged from top to bottom, and the fiberized powder falls downward from the sieve holes of the screen.

[0027] Specifically, in this embodiment, the mesh aperture ranges from 0.5-5 mm to accommodate the feeding of fibrous powders of varying composition ratios and to coordinate with the parameters of various components in the subsequent calendering step. For example, the apertures can be set to 0.5 mm, 0.6 mm, 0.7 mm, 1.0 mm, 3.0 mm, and so on, up to 5.0 mm. The vibration frequency of the vibrating mesh 11 ranges from 0 to 100 Hz. When the vibration rate of the vibrating mesh is set to 0, the powder can fall out by gravity, or when the vibrating mesh 11 vibrates, it is shaken out by the vibration of the vibrating mesh 11. Specifically, the vibration frequency of the vibrating mesh 11 can be set to 0 Hz, 6 Hz, 10 Hz, 20 Hz, 50 Hz, 80 Hz, and so on, up to 100 Hz.

[0028] S2, providing a pair of first rollers 20 with a roller diameter of d1, setting the pressure of the first rollers 20 to t1, and rolling the fiberized powder by the pair of first rollers 20 to obtain an initial film sheet 300 of initial thickness.

[0029] After being unloaded by the unloading structure 10, the fiberized powder is rolled by a pair of first rollers 20 in this step to obtain an initial film sheet 300 of initial thickness. When the powder is pressed into the initial film sheet 300, the powder gradually falls from the gap between the two first rollers 20 and is pressed into a film by the first rollers 20. In this embodiment, each first roller 20 is plated with a metallic chromium layer and is connected to a drive mechanism so that it can be driven to rotate by its own drive mechanism, so that each has a different rotation speed. In this way, a speed difference is formed between the two first rollers 20, which can generate a traction force for the forward movement of the obtained initial film sheet 300. At the same time, the first roller 20 and the second roller 40 in this embodiment are connected to respective heating mechanisms so that the first roller 20 and the second roller 40 can be heated to different temperatures, so that the film has different extension surfaces.

[0030] Specifically, in this embodiment, 10 cm ≤ d1 ≤ 30 cm; 0.8 tons ≤ t1 ≤ 8 tons, that is, a smaller roller diameter and a smaller pressure are used to initially press the fiber powder into a film.

[0031] Furthermore, in this embodiment, the rotational speed of the first roller 20 is V1. Specifically, the rotational speed range of V1 is 0<V1≤1800rpm, and the temperature range is 50℃≤T1≤200℃. The aforementioned roller diameter and pressure are combined to enable the powder to initially form a film, and a relatively low pressure is used to ensure the flexibility of the resulting initial film sheet 300 and reduce the degree of damage to the film during subsequent thinning and adjustment. At the same time, the temperature of the first roller 20 is adjusted according to the different components of the actual fiberized powder. Through this temperature control, the temperature of the first roller 20 is neither too low, which would prevent the powder from being heated and thus prevent the powder from forming a film quickly, nor too high, which would result in the surface temperature of the first roller being too high and resulting in a low hardness, making film formation difficult. At the same time, excessive temperature would damage the powder.

[0032] Specifically, the temperature of the first roller 20 in this embodiment is preferably in the range of 30° C. to 100° C. In actual production, the set temperature of the first roller 20 can be adjusted according to the composition of different powder materials.

[0033] After the initial film 300 is obtained in this step, the initial thickness of the initial film 300 is controlled to be in the range of 0.2 mm to 1.0 mm, so that the initial film 300 has a certain thickness and can be used for subsequent thinning processing.

[0034] S3 , the cutting structure 30 cuts the edge of the primary membrane 300 to obtain a membrane with smooth edges.

[0035] After the primary membrane sheet 300 is initially obtained, the primary membrane sheet 300 is cut in this step.

[0036] Specifically, the cutting structure 30 in this embodiment includes a support roller 31, a trimming knife 32, a powder suction nozzle 33 and a dust removal box 34. The support roller 31 is used to support the initial film sheet 300, and the trimming knife 32 is used to cut the edge of the initial film sheet 300 so that the edge of the film sheet can have a certain flatness. The powder suction nozzle 33 is used to suck away the debris and dust generated during the cutting process of the trimming knife 32, and the dust removal box 34 is used to collect the debris and dust adsorbed by the powder suction nozzle 33. In this way, in this step, the flatness of the initial film sheet 300 is adjusted by the trimming knife 32, and at the same time, the powder and debris are prevented from flying into the environment through the adsorption of the powder suction nozzle 33 and the collection of the dust removal box 34.

[0037] As will be appreciated, since the primary film sheet 300 has an extended length and a width, and has two side edges along the width direction, the cutting structure 30 in this embodiment includes two oppositely disposed trimming blades 32, with each trimming blade 32 being used to cut the edge of the primary film sheet 300. Furthermore, to adjust the cutting width, the distance between each trimming blade 32 and the center of the primary film sheet 300 is adjustable, and the travel speed of the trimming blades 32 is adapted to the travel speed of the primary film sheet 300.

[0038] S4, providing a pair of second rollers 40 with a roller diameter of d2, where d2 is less than d1, setting the pressure of the second rollers 40 to t2, where t2 is less than t1, and performing the initial thinning on the primary film 300 by the pair of second rollers 40 to obtain a secondary film of secondary thickness.

[0039] After the cutting in the above steps is completed, in this step the thickness of the primary film 300 is adjusted to obtain a secondary film of a secondary thickness.

[0040] Specifically, the roller diameter d2 of the second roller 40 in this embodiment is in the range of 5cm≤d2≤20cm, and the pressure t2 is in the range of 0.5 tons≤t2≤7 tons, both of which are smaller than the roller diameter and pressure of the first sub-roller 10. In this way, the smaller roller diameter and pressure enable the second roller 20 to have a faster walking speed, so as to achieve rapid adjustment of the compaction degree of the initial membrane sheet 300. At the same time, the component force of the second pressing roller 40 in the direction perpendicular to the membrane sheet is small, so that the initial membrane sheet 300 is initially extended to prepare for secondary thinning.

[0041] Furthermore, in this embodiment, the rotation speed of the second roller 40 is V2, and V2>V1 is set so that the roller can have a higher linear speed during the thinning process, thereby improving the film forming efficiency. Specifically, 500rpm≤V2≤2000rpm.

[0042] The temperature of the second roller 40 is T2, where T1 ≥ T2. Specifically, 50°C ≤ T2 ≤ 200°C. The temperatures of the first and second rollers 20 and 40 are adjusted based on the different components of the actual fiberized powder, or the same components in different proportions. This temperature control ensures that the temperature of the second roller 40 is neither too low nor too low to heat the membrane, thereby creating greater friction and facilitating expansion. At the same time, the temperature of the second roller 40 is neither too high nor too high to damage the membrane if it contacts the surface.

[0043] Furthermore, the two second rollers 40 of this embodiment are each connected to a driving mechanism so that they can be driven to rotate by their respective driving mechanisms so that each has a different rotational speed, so that the two second rollers 40 can have a speed difference, thereby causing a traction force to be generated on the diaphragm by the speed difference to drive the secondary diaphragm forward; at the same time, the second rollers 40 of this embodiment are connected to their respective heating mechanisms so that the two second rollers 40 can be heated to different temperatures. In this way, there can be a temperature difference when the two second rollers 40 are heated by the heating mechanism, so as to achieve different ductility on both sides of the diaphragm.

[0044] Furthermore, the components used in the initial thinning process in this embodiment also include a first scraper 41 and a first guide roller 42; the first scraper 41 applies downward pressure to the film adhered to the surface of the second roller 40 to separate the film from the surface of the second roller 40;

[0045] The thickness and compaction of the primary film 300 are initially adjusted by the second roller 40 , specifically, a rough adjustment with a faster travel speed;

[0046] In this way, after the initial thinning of the primary diaphragm 300 in this step, the thickness of the secondary diaphragm prepared is controlled to be in the range of 0.1mm-0.3mm, so that the secondary diaphragm has a certain thickness, preparing for the subsequent diaphragm adjustment structure to achieve the target thickness of the target diaphragm 500.

[0047] In step S5, at least one pair of third rollers 50 with a roller diameter of d3, where d3>d1, is provided. The pressure of the third rollers 50 is set to t3, where t3>t1. The secondary film is thinned twice by the third rollers 50 to obtain a target film 500 with a target thickness.

[0048] After completing the pre-thinning in the above step, the thickness and compaction of the secondary diaphragm are adjusted again in this step. Specifically, compared with the initial adjustment, this step is a fine adjustment of the diaphragm.

[0049] Specifically, the roller diameter d3 of the third roller 50 in this embodiment is set to d3>d1>d2, and the pressure t3 of the third roller 50 is set to t3>t1>t2, that is, after the powder is formed into a film and initially thinned, the roller with the largest roller diameter and the roller with the largest pressure are used in the final thinning step to achieve fine adjustment of the thickness and compaction of the membrane.

[0050] Since the pressure roller exerts a first force component parallel to the extension direction of the film and a second force component perpendicular to the film when compressing the film, by setting the third roller 50 with the largest roller diameter, the greater the weight of the third roller 50 and the pressure applied to the third roller 50, the greater the vertical force component that can be applied to the film. Therefore, in the final pressing step, this embodiment uses the largest roller diameter and the maximum pressure to perform secondary adjustments to the thickness and compaction of the secondary film, thereby obtaining a final film with the desired target thickness and compaction. Simultaneously, setting the speed of the second roller 40 to be similar to that of the second roller 40 allows for matching the travel speed of the second pressure roller 40 to the travel speed of the film conveyed by the second roller 40.

[0051] Among them, the roller diameter d3 of the third roller 50 is set in a large range: 15mm≤d3≤60mm, and the pressure range is: 1 ton≤t3≤10 tons, so that the roller diameter of the third roller 50 can have a larger roller diameter and pressure relative to the first roller 20 and the second roller 40, so as to achieve the effect of adjusting the membrane thickness and compaction degree to the target parameters.

[0052] Furthermore, the speed V3 range of the third roller 50 in this embodiment is set to: V2≥V3>V1, specifically, 500rpm≤V3≤2000rpm; the temperature of the third roller 50 in this embodiment is set to the minimum, T1≥T2>T3, specifically, 0℃≤T3≤150℃, so that the third roller 50 can have a smaller speed and temperature and perform fine adjustment on the diaphragm.

[0053] It can be understood that when the third roller 50 is used for pressing, a second scraper 51 is also provided to apply downward pressure to the film adhered to the surface of the third roller 50 to separate the film from the surface of the third roller 50 .

[0054] Specifically, the thickness of the final membrane obtained in this embodiment ranges from 0.06 mm to 0.2 mm.

[0055] Specifically, the roller diameter d1 of the first roller 20 in this embodiment can be set to values ​​such as 10 cm, 12 cm, 15 cm, 17 cm, 20 cm, 30 cm, etc.; the roller diameter d2 of the second roller 40 can be set to values ​​such as 5 cm, 6 cm, 7 cm, 10 cm, 15 cm, 20 cm, etc., and the roller diameter d3 of the third roller 50 can be set to values ​​such as 15 cm, 30 cm, 45 cm, 50 cm, 55 cm, 60 cm, etc.; the pressure t1 of the first roller 20 can be set to values ​​such as 0.8 tons, 1 ton, 2 tons, 3 tons, 5 tons, 8 tons, etc.; the pressure t2 of the second roller 40 can be set to values ​​such as 0.5 ton, 1 ton, 2 tons, 4 tons, 6 tons, 7 tons, etc.; the pressure t3 of the third roller 50 can be set to values ​​such as 1 ton, 2 tons, 4 tons, 6 tons, 8 tons, 10 tons, etc.

[0056] Furthermore, in this embodiment, the gap between the two third rollers 50 is adjustable, and the precision tolerance between the two is ±1 μm, so that the thickness of the target membrane 500 can be finely adjusted.

[0057] It can be understood that after completing the preparation of the above-mentioned dry electrode membrane, the preparation method of the dry electrode membrane of this embodiment further includes a winding step, in which the final membrane is wound by a winding structure for use in preparing the electrode in the next step.

[0058] The test data of the diaphragm obtained according to the preparation method of the dry-process electrode diaphragm in this embodiment is shown in Figure 2, wherein curve a is a schematic diagram of the tensile strength of the diaphragm prepared by the conventional process on the existing market, curve b is a schematic diagram of the tensile strength of the initial diaphragm obtained by using the first roller 20, curve c is a schematic diagram of the tensile strength of the secondary diaphragm obtained after the initial thinning of the initial diaphragm by the second roller 40, and curve d is a schematic diagram of the tensile strength of the target diaphragm obtained after the secondary diaphragm is thinned for the second time by using the third roller 50.

[0059] Specifically, it can be seen from FIG2 that the thick film sheet prepared by a conventional dry process through a single film forming process is thinned to the target surface density and thickness, and its strength and toughness are poor, with a tensile strength of 0.62 MPa and an elongation at break of 10.48%.

[0060] The initial film obtained by the first roller 20 had a tensile strength of 1.15 MPa and an elongation at break of 9.86%, indicating that the initial film prepared by the first roller 20 was stronger and tougher than that produced by conventional processes.

[0061] The secondary membrane produced by the second roller 40, after thinning the primary membrane, was tested to have a tensile strength of 1.39 MPa and an elongation at break of 8.59%. This indicates that the secondary membrane produced by thinning with the second roller 40 exhibits superior toughness to both the conventional process and the primary membrane produced with the first roller 20, demonstrating that controlling the parameters of the thinning roller can effectively improve membrane performance.

[0062] The target membrane obtained by the third roller 50 was subjected to secondary thinning of the initial membrane. Testing of the target membrane revealed a tensile strength of 1.53 MPa and an elongation at break of 8.24%. These data demonstrate that the toughness of the target membrane obtained by secondary thinning of the initial membrane using the second roller 40 and third roller 50 in this embodiment is enhanced, effectively improving the performance of the resulting membrane.

[0063] The above-mentioned dry-process electrode membrane preparation method is to set the roller diameter and pressure of the first roller 20 for pressing the powder into a membrane and the second roller 40 and the third roller 50 for adjusting the membrane thickness and compaction once and twice to d3>d1>d2, t3>t1>t2. When pressing the powder into a membrane and adjusting it, the powder can first be pressed into an initial membrane by the first roller 20 with a larger roller diameter and pressure, and then the initial membrane 300 can be quickly roughly adjusted at a faster walking speed by the second roller 40 with a smaller roller diameter and pressure, so that the thickness and compaction of the membrane are preliminarily adjusted. Finally, the membrane is finely adjusted with a large pressure by the third roller 50 with the largest roller diameter and maximum pressure, so that the obtained membrane can meet the required thickness and have a higher compaction. At the same time, the membrane has mechanical properties such as higher strength and higher toughness, and at the same time, the membrane has an excellent pore structure to improve the battery electrical performance when the membrane is used in the battery, and has lower tortuosity.

[0064] Please refer to FIG. 3 . In a second embodiment, the present application further provides a dry-process electrode membrane preparation device 200 , which includes a pair of first rollers 20 , a pair of second rollers 40 and at least a pair of third rollers 50 .

[0065] Among them, a pair of first rollers 20 are used to roll the fiberized powder to obtain an initial film sheet 300 of initial thickness, the diameter of the first roller is d1, and the pressure of the first roller 20 is t1; a pair of second rollers 40 are arranged downstream of the pair of first rollers 20, and are used to thin the initial film sheet 300 to obtain a secondary film sheet of secondary thickness, the diameter of the second roller is d2, and the pressure of the second roller 40 is t2; at least one pair of third rollers 50 are arranged downstream of the second roller 40, and are used to thin the secondary film sheet for the second time to obtain a final film sheet of final thickness, the diameter of the third roller 50 is d3, and the pressure of the second roller 40 is t3, wherein d3>d1>d2, t3>t1>t2.

[0066] The above-mentioned dry-process electrode membrane preparation equipment 200 sets the roller diameters and pressures of the first roller 20 for pressing the powder into a membrane and the second roller 40 and the third roller 50 for adjusting the membrane thickness and compaction once and twice to d3>d1>d2, t3>t1>t2. When pressing the powder into a membrane and adjusting it, the powder can first be pressed into an initial membrane by the first roller 20 with a larger roller diameter and pressure, and then the initial membrane 300 can be quickly roughly adjusted at a faster walking speed by the second roller 40 with a smaller roller diameter and pressure, so that the thickness and compaction of the membrane are preliminarily adjusted. Finally, the membrane is finely adjusted with a large pressure by the third roller 50 with the largest roller diameter and maximum pressure, so that the obtained membrane can meet the required thickness and have a higher compaction. At the same time, the membrane has mechanical properties such as higher strength and higher toughness, and at the same time, the membrane has an excellent pore structure to improve the battery electrical performance when the membrane is used in a battery, and has lower tortuosity.

[0067] Furthermore, the preparation equipment of this embodiment also includes a feeding structure 10 for feeding a pair of first rollers 20. The feeding structure 10 includes a vibrating screen 11 and a movable material trough 12 arranged below the vibrating screen 11. The vibrating screen 11 includes two layers of screens separated from top to bottom. The movable material trough 12 is used to receive the powder dropped from the vibrating screen 11 for feeding out. In this way, after the powder is poured on the vibrating screen 11, the vibrating screen 11 vibrates to allow the powder to pass through the two layers of screens and gradually fall onto the movable material trough 12. The movable material trough 12 can be gradually adjusted from a vertical state to a horizontal state to drive the powder to move, so as to gradually sprinkle the powder, and at the same time adjust the speed at which the powder is sprinkled to avoid accumulation or agglomeration of the powder.

[0068] It can be understood that the present embodiment further includes a second guide roller 60 to reverse the direction of the primary film 300 and guide it to the second roller 40 .

[0069] Among them, the vibrating screen 11 used in this embodiment can realize the granulation of the fiberized powder, and at the same time, powders of different particle sizes can be obtained through screens with different apertures, different film-forming efficiencies can be controlled, and the effect of preventing the fiberized powder from agglomerating can be achieved to ensure the uniformity and continuity of the material discharge.

[0070] In addition, in order to ensure the flatness of the edge of the final diaphragm produced, the preparation equipment of the dry-process electrode diaphragm also includes a cutting structure 30, which is used to cut the edge of the initial diaphragm 300, including a support roller 31, a trimming knife 32, a powder suction nozzle 33 and a dust removal box 34. The support roller 31 is used to support the initial diaphragm 300, the trimming knife 32 is used to cut the edge of the initial diaphragm 300, the powder suction nozzle 33 is used to suck away the debris and dust generated during the cutting process of the trimming knife 32, and the dust removal box 34 is used to collect the debris and dust adsorbed by the powder suction nozzle 33. By setting the trimming knife 32, the flatness of the initial diaphragm 300 can be adjusted by the trimming knife 32 in this step. At the same time, the adsorption of the powder suction nozzle 33 and the collection of the dust removal box 34 can prevent powder and debris from flying into the environment.

Claims

1. Preparation method of dry-process pole piece diaphragm, comprising: Providing a pair of first rollers with a roll diameter of d1, setting the pressure of the first rollers as t1, and roll-pressing the fibrillated powder through the pair of first rollers to obtain a primary diaphragm with a primary thickness; Providing a pair of second rollers with a roll diameter of d2, and d2 < d1, setting the pressure of the second rollers as t2, and t2 < t1, and performing primary thinning on the primary diaphragm through the pair of second rollers to obtain a secondary diaphragm with a secondary thickness; Providing at least a pair of third rollers with a roll diameter of d3, and d3 > d1, setting the pressure of the third rollers as t3, and t3 > t1, and performing secondary thinning on the secondary diaphragm through the third rollers to obtain a target diaphragm with a target thickness.

2. The preparation method of the dry-type electrode sheet diaphragm according to claim 1, wherein, 10 cm ≤ d1 ≤ 30 cm; 5 cm ≤ d2 ≤ 20 cm; 15 cm ≤ d3 ≤ 60 cm.

3. The preparation method of the dry-type electrode sheet film according to claim 1 or 2, wherein, The rotation speed of the first rollers is V1, the rotation speed of the second rollers is V2, and the rotation speed of the third rollers is V3, wherein, V2 ≥ V3 > V1.

4. The preparation method of dry-process pole piece diaphragm according to claim 3, wherein, 0 rpm < V1 ≤ 1800 rpm; 500 rpm ≤ V2 ≤ 2000 rpm; 500 rpm ≤ V3 ≤ 2000 rpm.

5. The method for preparing a dry electrode sheet according to claim 1 or 2, wherein, 0.8 ton ≤ t1 ≤ 8 tons, 0.5 ton ≤ t2 ≤ 7 tons, 1 ton ≤ t3 ≤ 10 tons.

6. The preparation method of the dry electrode sheet film according to claim 1 or 2, wherein, The temperature of the first rollers is T1, the temperature of the second rollers is T2, and the temperature of the third rollers is T3; Wherein, T1 ≥ T2 > T3.

7. The method for preparing the dry electrode sheet according to claim 6, wherein, 50 °C ≤ T1 ≤ 200 °C, 50 °C ≤ T2 ≤ 200 °C, 0 °C ≤ T3 ≤ 150 °C.

8. The preparation method of dry-process pole piece diaphragm according to claim 1 or 2, wherein, The thickness range of the primary diaphragm is 0.2 mm - 1.0 mm; The thickness range of the secondary diaphragm is 0.1 mm - 0.3 mm; The thickness range of the final diaphragm is 0.06 mm - 0.2 mm.

9. Preparation equipment of dry-process pole piece diaphragm, comprising: A pair of first rollers, disposed downstream of the blanking structure, for roll-pressing the fibrillated powder to obtain a primary diaphragm with a primary thickness, the diameter of the first press roller is d1, and the pressure of the first rollers is t1; A pair of second rollers, disposed downstream of the pair of first rollers, for performing primary thinning on the primary diaphragm to obtain a secondary diaphragm with a secondary thickness, the diameter of the second press roller is d2, and the pressure of the second rollers is t2; At least a pair of third rollers, disposed downstream of the pair of second rollers, for performing secondary thinning on the secondary diaphragm to obtain a target diaphragm with a target thickness, the diameter of the third press roller is d3, and the pressure of the second rollers is t3, Wherein, d3 > d1 > d2, t3 > t1 > t2.

10. The preparation equipment for the dry-type electrode sheet diaphragm according to claim 9, wherein the preparation equipment for the dry-type electrode sheet diaphragm further comprises a cutting structure, which is used for cutting the edge of the initial diaphragm. The cutting structure includes a support roller, a trimming knife, a powder suction nozzle and a dust collection box. The support roller is used for supporting the initial diaphragm, the trimming knife is used for cutting the edge of the initial diaphragm, the powder suction nozzle is used for sucking away the debris and dust generated during the cutting process of the trimming knife, and the dust collection box is used for collecting the debris and dust adsorbed by the powder suction nozzle.

11. The manufacturing equipment for the dry-type electrode sheet diaphragm according to claim 9, wherein, The preparation equipment for the dry-type electrode sheet diaphragm further comprises a feeding structure for feeding materials to a pair of the first rolling rollers. The feeding structure includes a vibrating screen and a movable material trough arranged below the vibrating screen. The movable material trough is used for receiving the powder dropped from the vibrating screen and sending it out.

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