Preparation method and equipment of dry-process electrode membrane

Abstract

The present invention discloses a preparation method and preparation equipment of a dry electrode film. The preparation method of the dry electrode film comprises providing a pair of first rollers with a roller diameter of d1, setting the pressure of the first rollers to t1, rolling the fibrous powder by the pair of first rollers to obtain an initial film of initial thickness; providing a pair of second rollers with a roller diameter of d2, and d2<d1, setting the pressure of the second rollers to t2, and t2<t1, and performing primary thinning on the initial film by the pair of second rollers to obtain a secondary film of secondary thickness; providing at least a pair of third rollers with a roller diameter of d3, and d3>d1, setting the pressure of the third rollers to t3, and t3>t1, and performing secondary thinning on the secondary film by the third roller to obtain a target film of target thickness. The target film prepared in this embodiment has better strength and more suitable toughness characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode plates, and in particular to a method and equipment for preparing a dry-process electrode film. Background Art

[0002] In the preparation process of lithium-ion batteries, in recent years, a dry technology that 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.

[0003] In the preparation process of dry electrodes, active materials, conductive agents, and binders are subjected to shear force at a specific temperature to fiberize to obtain fiberized powder, which is then rolled into a film and then rolled up. In existing membranes prepared by dry technology, the membrane strength is insufficient due to improper matching of roller size and pressure. Utility Model Content

[0004] In order to solve at least one problem existing in the above-mentioned prior art, according to a first aspect of the present invention, a method for preparing a dry electrode membrane is provided, comprising:

[0005] Providing a pair of first rollers with a roller diameter of d1, setting the pressure of the first rollers to be t1, and rolling the fiberized powder by the pair of first rollers to obtain an initial film sheet with an initial thickness;

[0006] Providing a pair of second rollers with a roller diameter of d2, and d2<d1, setting the pressure of the second rollers to t2, and t2<t1, and performing primary thinning on the primary film by the pair of second rollers to obtain a secondary film with a secondary thickness;

[0007] At least one pair of third rollers with a roller diameter of d3, and d3>d1 is provided, the pressure of the third rollers is set to t3, and t3>t1, and the secondary film is thinned twice by the third rollers to obtain a target film with a target thickness;

[0008] Among them, 10cm≤d1≤30cm; 5cm≤d2≤20cm; 15cm≤d3≤60cm; 0.8 tons≤t1≤8 tons, 0.5 tons≤t2≤7 tons, 1 ton≤t3≤10 tons.

[0009] In some embodiments, the rotation speed of the first roller is V1, the rotation speed of the second roller is V2, and the rotation speed of the third roller is V3, wherein V2≥V3>V1

[0010] In some embodiments, 0 rpm<V1≤1800 rpm; 500 rpm≤V2≤2000 rpm; 500 rpm≤V3≤2000 rpm.

[0011] In some embodiments, the temperature of the first roller is T1, the temperature of the second roller is T2, and the temperature of the third roller is T3; wherein T1≥T2>T3.

[0012] In some embodiments, 50°C≤T1≤200°C, 50°C≤T2≤200°C, and 0°C≤T3≤150°C.

[0013] In some embodiments, the thickness of the primary film is in the range of 0.2 mm to 1.0 mm;

[0014] The thickness of the secondary diaphragm ranges from 0.1mm to 0.3mm;

[0015] The target film has a thickness ranging from 0.06 mm to 0.2 mm.

[0016] The first aspect of the present invention provides a dry process electrode membrane preparation device, comprising:

[0017] A pair of first rollers, arranged downstream of the material feeding structure, for rolling the fiberized powder to obtain an initial film sheet with an initial thickness, wherein the diameter of the first rollers is d1, and the pressure of the first rollers is t1;

[0018] A pair of second rollers, disposed downstream of the pair of first rollers, for performing primary thinning on the primary film to obtain a secondary film of secondary thickness, wherein the diameter of the second rollers is d2, and the pressure of the second rollers is t2;

[0019] At least one pair of third rollers is disposed downstream of the pair of second rollers, and is used to perform 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.

[0020] Among them, d3>d1>d2, t3>t1>t2, and 10cm≤d1≤30cm; 5cm≤d2≤20cm; 15cm≤d3≤60cm; 0.8 tons≤t1≤8 tons, 0.5 tons≤t2≤7 tons, 1 ton≤t3≤10 tons.

[0021] In some embodiments, the preparation equipment of the dry electrode membrane also includes a cutting structure, which is used to cut the edge of the initial membrane. The cutting structure includes a support roller, a cutting knife, a powder suction nozzle and a dust removal box. The support roller is used to support the initial membrane, the cutting knife is used to cut the edge of the initial membrane, the powder suction nozzle is used to suck away the debris and dust generated by the cutting knife during the cutting process, and the dust removal box is used to collect the debris and dust sucked by the powder suction nozzle.

[0022] In some embodiments, the preparation equipment of the dry electrode membrane also includes a feeding structure for feeding material to a pair of the first rollers, and the feeding structure includes a vibrating screen and a movable material trough arranged below the vibrating screen, and the movable material trough is used to receive the powder dropped from the vibrating screen and feed it out.

[0023] In summary, the fully dry electrode diaphragm preparation method and preparation equipment provided by the present invention have the following technical effects:

[0024] 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 the powder is pressed into a film and adjusted, 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 roughly 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 can be preliminarily adjusted, and finally the third roller with the maximum roller diameter and maximum pressure can be finely adjusted with a large pressure to make the obtained film meet the required thickness and have a higher compaction degree. At the same time, the film has higher strength and more suitable mechanical properties such as toughness, 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 a lower tortuosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic flow chart of a method for preparing a dry electrode membrane according to an embodiment of the present invention;

[0026] Figure 2 A schematic diagram showing a comparison of the tensile strength of a diaphragm prepared in an embodiment of the present invention and a diaphragm prepared by a conventional process;

[0027] Figure 3 It is a schematic structural diagram of a dry-process electrode membrane preparation device according to an embodiment of the present invention.

[0028] Figure: 200-dry process electrode membrane preparation equipment, 10-feeding structure, 11-vibrating screen, 12-movable material trough, 20-first rolling roller, 30-cutting structure, 31-supporting roller, 32-edge trimming knife, 33-powder suction nozzle, 34-dust removal box, 40-second rolling roller, 41-first scraper, 42-first guide roller, 50-third rolling roller, 51-second scraper, 60-second guide roller, 70-winding structure, 300-primary membrane; 400-secondary membrane, 500-target membrane. DETAILED DESCRIPTION

[0029] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0033] See also Figure 1 , a method 100 for preparing a dry electrode film provided by an embodiment of the present invention comprises the following steps:

[0034] S1, feeding the fiberized powder through the feeding structure 10.

[0035] Among them, the fiberized powder in this embodiment includes but is not limited to active materials, conductive agents and binders, and the fiberized powder is formed by applying shear force to the active materials, conductive agents and binders. 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.; the binder includes but is not limited to one or more combinations of polytetrafluoroethylene, tetrafluoroethylene, polyacrylic acid, carboxymethyl cellulose, polyethylene glycol, polyvinyl pyrrolidone, etc.

[0036] 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 .

[0037] Specifically, the material discharge structure 10 of this embodiment 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 arranged from top to bottom, and the fiberized powder falls downward from the screen holes of the screen.

[0038] Specifically, in this embodiment, the aperture range of the screen is set to 0.5-5mm to match the feeding of fibrous powders with different composition ratios, so as to adapt to the parameters of various components in the subsequent calendering step, for example, it can be set to 0.5mm, 0.6mm, 0.7mm, 1.0mm, 3.0mm...5.0mm. The vibration frequency of the vibrating screen 11 is 0-100HZ. When the vibration rate of the vibrating drying net is set to 0, the powder can fall out by its own gravity, or when the vibrating screen 11 vibrates, it is vibrated out by the vibration of the vibrating screen 11. Specifically, the vibration frequency of the vibrating screen 11 is set to 0HZ, 6HZ, 10HZ, 20HZ, 50HZ, 80HZ...100HZ.

[0039] 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 with an initial thickness.

[0040] After the material is unloaded through the unloading structure 10, in this step, the fibrous powder is rolled by a pair of first rollers 20 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 to be pressed into a film by the first rollers 20. In this embodiment, the surface of each first roller 20 is plated with a metal chromium layer, and each is connected to a driving mechanism so that it can be driven to rotate by its own driving 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 initial film sheet 300; at the same time, the first roller 20 and the second roller 40 in this embodiment are connected to their own 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.

[0041] Specifically, in this embodiment, 10 cm ≤ d1 ≤ 30 cm; 0.8 ton ≤ t1 ≤ 8 ton, that is, a smaller roller diameter and a smaller pressure are used to initially press the fiber powder into a film.

[0042] Furthermore, the rotation speed of the first roller 20 in this embodiment is V1. Specifically, the rotation speed range of V1 is 0<V1≤1800rpm, and the temperature range is 50℃≤T1≤200℃. The above roller diameter and pressure are matched to enable the powder to initially form a film, and a smaller pressure is used to ensure the flexibility of the initial film sheet 300 obtained, and reduce the degree of damage to the film sheet during the subsequent thinning adjustment process. At the same time, the temperature of the first roller 20 is adjusted according to the different components in the actual fiberized powder. Through this temperature control, the temperature of the first roller 20 is not too low, so that the powder cannot be heated, resulting in the powder being unable to form a film at a faster speed, and it cannot be too high, resulting in the surface temperature of the first roller being too high, resulting in a lower hardness, which is not convenient for film formation, and at the same time, the high temperature causes damage to the powder.

[0043] 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.

[0044] 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-1.0 mm, so that the initial film 300 has a certain thickness and can be used for subsequent thinning treatment.

[0045] S3, the cutting structure 30 cuts the edge of the primary film 300 to obtain a film with smooth edges.

[0046] After the initial film sheet 300 is initially obtained, the initial film sheet 300 is cut in this step.

[0047] 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, 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.

[0048] It can be understood that, since the primary film 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 trimming knives 32 arranged opposite to each other, and one trimming knife 32 is used to cut the edge of the primary film 300. At the same time, in order to adjust the cutting width, the distance between each trimming knife 32 and the center of the primary film 300 can be adjusted, and the travel speed of the trimming knife 32 is adapted to the travel speed of the primary film 300.

[0049] S4, providing a pair of second rollers 40 with a roller diameter of d2, where d2<d1, setting the pressure of the second rollers 40 to t2, where t2<t1, and performing initial thinning on the primary film 300 by the pair of second rollers 40 to obtain a secondary film of secondary thickness.

[0050] 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 secondary thickness.

[0051] 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. Thus, 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 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.

[0052] Furthermore, the rotation speed of the second roller 40 in this embodiment is V2, and V2>V1 is set so that the roller can have a larger linear speed during the thinning process, thereby improving the forming efficiency of the membrane. Specifically, 500rpm≤V2≤2000rpm.

[0053] The temperature of the second roller 40 is T2, T1≥T2. Specifically, 50℃≤T2≤200℃. The temperatures of the first roller 20 and the second roller 40 are adjusted according to the different components in the actual fiberized powder or the same components but different proportions. Through this temperature control, the temperature of the second roller 40 is not too low, and the diaphragm cannot be heated, which causes the diaphragm to have a large friction force and is easy to extend; at the same time, the temperature of the second roller 40 is not too high, and when it contacts the surface of the diaphragm, it causes damage to the diaphragm.

[0054] Furthermore, the two second rollers 40 of the present embodiment are respectively connected to a driving mechanism so that they can be driven to rotate through their respective driving mechanisms so that they each have 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 to move forward; at the same time, the second rollers 40 of the present 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.

[0055] 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;

[0056] The thickness and compaction of the initial film 300 are initially adjusted by the second roller 40, specifically, a rough adjustment with a faster travel speed;

[0057] Thus, after the initial thinning of the primary film 300 in this step, the thickness of the secondary film is controlled to be in the range of 0.1mm-0.3mm, so that the secondary film has a certain thickness, preparing for the subsequent film adjustment structure to achieve the target film 500 of the target thickness.

[0058] Step S5, providing at least one pair of third rollers 50 with a roller diameter of d3, and d3>d1, setting the pressure of the third rollers 50 to t3, and t3>t1, and performing secondary thinning on the secondary film by the third rollers 50 to obtain a target film 500 with a target thickness.

[0059] After completing the pre-thinning in the above step, the thickness and compactness of the secondary membrane are adjusted again in this step. Specifically, compared with the initial adjustment, this step is to make a fine adjustment to the membrane.

[0060] 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 maximum pressure are used in the final thinning step to achieve fine adjustment of the thickness and compaction of the membrane.

[0061] Since the roller has a first force component parallel to the extension direction of the diaphragm and a second force component perpendicular to the diaphragm when pressing the diaphragm, by setting the third roller 50 with the largest roller diameter, the greater the weight of the third roller 50, and the greater the pressure applied to the third roller 50, the greater the force component in the vertical direction that can be applied to the diaphragm. Therefore, in the final pressing step, this embodiment uses the largest roller diameter and the largest pressure to make a secondary adjustment to the thickness and compaction of the secondary diaphragm, so as to obtain the target diaphragm with the desired target thickness and compaction. At the same time, setting a speed that is not much different from the second roller 40 can match the travel speed of the second roller 40 to adapt to the travel speed of the diaphragm conveyed by the second roller 40.

[0062] Among them, the roller diameter d3 of the third roller 50 is set in a large range: 10mm≤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.

[0063] Furthermore, the speed 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.

[0064] It can be understood that when the third roller 50 is used for pressing, a second scraper 51 is also provided, and a downward pressure is applied to the membrane adhered to the surface of the third roller 50 by the second scraper 51 to separate the membrane from the surface of the third roller 50 .

[0065] Specifically, the target film thickness obtained in this embodiment ranges from 0.06 mm to 0.2 mm.

[0066] Specifically, the roller diameter d1 of the first roller 20 in the present embodiment can be set to values ​​such as 10cm, 12cm, 15cm, 17cm, 20cm, 30cm, etc.; the roller diameter d2 of the second roller 40 can be set to values ​​such as 5cm, 6cm, 7cm, 10cm, 15cm, 20cm, etc., and the roller diameter d3 of the third roller 50 can be set to values ​​such as 15cm, 30cm, 45cm, 50cm, 55cm, 60cm, 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.

[0067] 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 obtained in the end can be finely adjusted.

[0068] 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 also includes a winding step, in which the target membrane is rolled up by a winding structure for use in preparing the electrode in the next step.

[0069] The test data of the membrane obtained according to the preparation method of the dry electrode membrane in this embodiment is as follows: Figure 2 As shown, 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 thinning of the secondary diaphragm by the third roller 50.

[0070] Specifically, by Figure 2 It can be seen that the thick film sheet prepared by one-time film formation using an ordinary dry process is thinned to the target surface density and thickness, and its strength and toughness are poor, with a tensile strength of 0.62MPa and an elongation at break of 10.48%.

[0071] The initial film obtained by the first rolling roller 20 has a tensile strength of 1.15 MPa and a breaking elongation of 9.86%, indicating that the initial film prepared by the first rolling roller 20 has better toughness than the ordinary process.

[0072] The secondary film obtained by the second roller 40, after thinning the primary film, was tested to have a tensile strength of 1.39 MPa and a breaking elongation of 8.59%. It can be concluded that the strength and toughness of the secondary film obtained by the second roller 40 after thinning is better than that of the primary film obtained by the ordinary process and the first roller 20, indicating that the parameter control of the thinning roller can effectively improve the performance of the film.

[0073] The target film obtained by the third roller 50 was subjected to secondary thinning of the initial film, and the target film was tested, and the tensile strength was 1.53MPa and the elongation at break was 8.24%. The above data show that the toughness of the target film obtained by the second roller 40 and the third roller 50 in this embodiment after the initial film was subjected to secondary thinning by parameter control is improved, so that the performance of the film finally prepared is effectively improved.

[0074] The above-mentioned method for preparing dry electrode membranes is to set 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, so that when the powder is pressed into a membrane and adjusted, the powder can be first 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, and finally the membrane is finely adjusted with a large pressure by the third roller 50 with the maximum roller diameter and maximum pressure, so that the obtained membrane can meet the required thickness and have a higher compaction, and at the same time, the membrane has higher 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 applied to the battery, and at the same time has a lower tortuosity.

[0075] See also Figure 3 In a second embodiment, the present invention further provides a dry electrode membrane preparation device 200, comprising a pair of first rollers 20, a pair of second rollers 40 and at least a pair of third rollers 50.

[0076] 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 perform secondary thinning on the secondary film sheet to obtain a target 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.

[0077] The above-mentioned dry electrode membrane preparation equipment 200 sets 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, so that when pressing the powder into a membrane and adjusting it, the powder can be first 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, and finally the membrane is finely adjusted with a large pressure by the third roller 50 with the maximum roller diameter and maximum pressure, so that the obtained membrane can meet the required thickness and have a higher compaction, and at the same time, the membrane has higher 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 applied to the battery, and at the same time has a lower tortuosity.

[0078] Furthermore, the preparation equipment of this embodiment also includes a feeding structure 10 for feeding material to 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, and the movable material trough 12 is used to receive the powder dropped from the vibrating screen 11 for feeding out, so that after the powder is poured on the vibrating screen 11, the vibrating screen 11 vibrates to allow the powder to gradually pass through the two layers of screens and fall onto the movable material trough 12, and 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.

[0079] 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 .

[0080] Among them, the vibrating screen 11 used in this embodiment can realize the granulation of 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 material feeding.

[0081] In addition, in order to ensure the flatness of the edge of the target 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 trimming knife 32 can adjust the flatness of the initial diaphragm 300 in this step, and 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.

[0082] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A method for preparing a dry-process electrode film, characterized in that: include: Providing a pair of first rollers with a roller diameter of d1, setting the pressure of the first rollers to be t1, and rolling the fiberized powder by the pair of first rollers to obtain an initial film sheet with an initial thickness; Providing a pair of second rollers with a roller diameter of d2, and d2<d1, setting the pressure of the second rollers to t2, and t2<t1, and performing primary thinning on the primary film by the pair of second rollers to obtain a secondary film with a secondary thickness; At least one pair of third rollers with a roller diameter of d3, and d3>d1 is provided, the pressure of the third rollers is set to t3, and t3>t1, and the secondary film is thinned twice by the third rollers to obtain a target film with a target thickness; Among them, 10cm≤d1≤30cm; 5cm≤d2≤20cm; 15cm≤d3≤60cm; 0.8 tons≤t1≤8 tons, 0.5 tons≤t2≤7 tons, 1 ton≤t3≤10 tons.

2. The method for preparing a dry electrode film according to claim 1, characterized in that: The rotation speed of the first roller is V1, the rotation speed of the second roller is V2, and the rotation speed of the third roller is V3, wherein V2≥V3>V1.

3. The method for preparing a dry electrode film according to claim 2, characterized in that: 0rpm<V1≤1800rpm; 500rpm≤V2≤2000rpm; 500rpm≤V3≤2000rpm.

4. The method for preparing a dry electrode film according to claim 1, characterized in that: The temperature of the first roller is T1, the temperature of the second roller is T2, and the temperature of the third roller is T3; Among them, T1≥T2>T3.

5. The method for preparing a dry electrode film according to claim 4, characterized in that: 50℃≤T1≤200℃, 50℃≤T2≤200℃, 0℃≤T3≤150℃.

6. The method for preparing a dry electrode film according to claim 1, characterized in that: The thickness of the primary membrane is in the range of 0.2mm-1.0mm; The thickness of the secondary diaphragm ranges from 0.1mm to 0.3mm; The target film has a thickness ranging from 0.06 mm to 0.2 mm.

7. Dry-process electrode membrane preparation equipment, characterized in that: include: A pair of first rollers, arranged downstream of the material feeding structure, for rolling the fiberized powder to obtain an initial film sheet with an initial thickness, wherein the diameter of the first rollers 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 film to obtain a secondary film of secondary thickness, wherein the diameter of the second rollers is d2, and the pressure of the second rollers is t2; At least one pair of third rollers is disposed downstream of the pair of second rollers, and is used to perform 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. Among them, d3>d1>d2, t3>t1>t2, and 10cm≤d1≤30cm; 5cm≤d2≤20cm; 15cm≤d3≤60cm; 0.8 tons≤t1≤8 tons, 0.5 tons≤t2≤7 tons, 1 ton≤t3≤10 tons.

8. The dry process electrode film preparation equipment according to claim 7, characterized in that: The preparation equipment of the dry electrode membrane also includes a cutting structure, which is used to cut the edge of the initial membrane. The cutting structure includes a support roller, a cutting knife, a powder suction nozzle and a dust removal box. The support roller is used to support the initial membrane, the cutting knife is used to cut the edge of the initial membrane, the powder suction nozzle is used to suck away the debris and dust generated by the cutting knife during the cutting process, and the dust removal box is used to collect the debris and dust sucked by the powder suction nozzle.

9. The dry process electrode film preparation equipment according to claim 7, characterized in that: The equipment for preparing the dry electrode membrane also includes a feeding structure for feeding material to a pair of the first rollers. The feeding structure includes a vibrating screen and a movable trough arranged below the vibrating screen. The movable trough is used to receive the powder dropped from the vibrating screen and feed it out.

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