Dry-method pole piece preparation equipment and method

Abstract

The invention discloses dry-method pole piece preparation equipment and method.The dry-method pole piece preparation equipment comprises rolling equipment, the rolling equipment comprises a plurality of pressing roller units which are sequentially arranged, each pressing roller unit comprises a first pressing roller and a second pressing roller which are oppositely arranged, each first pressing roller is a middle-convex arc-shaped roller, and the diameter of each first pressing roller is gradually decreased from the middle to the two sides; according to the pole piece film forming device, the efficiency and quality of the pole piece film forming process are remarkably improved, and meanwhile, the environmental influence and the production cost are reduced.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a dry-process electrode preparation device and method. Background Art

[0002] The electrode film forming method is generally divided into wet film forming process and dry film forming process. The traditional wet process requires the use of solvents and then heating and drying them. This process will affect production efficiency and increase production costs. In the dry process, no solvent is needed. The electrode can be obtained by hot pressing the fiberized binder, active material and current collector. Compared with the wet process, the dry process has higher production efficiency and is more environmentally friendly.

[0003] The dry process usually uses two pairs of linear rollers to extrude the material. The rollers need to apply a large roller pressure. Due to the large roller pressure, a large roller diameter is required to ensure its rigidity. However, the minimum rolling thickness of the roller is related to the roller diameter. A large roller diameter will limit the minimum thickness that can be rolled.

[0004] Therefore, there is an urgent need for a dry electrode preparation device and method to solve the above problems. Summary of the invention

[0005] In view of this, the present invention discloses a dry-process electrode preparation device and method, which improves the efficiency and quality of the electrode film forming process, while reducing environmental impact and production costs. The technical solution of the present invention is implemented as follows:

[0006] The first aspect of the present invention discloses a dry-process electrode preparation device, including a rolling device, wherein the rolling device includes a plurality of sequentially arranged rolling units, wherein the rolling units include a first rolling roller and a second rolling roller that are relatively arranged, wherein the first rolling roller is a convex arc roller, wherein the diameter of the first rolling roller gradually decreases from the middle to both sides, and the curvature of the convex parts of the plurality of sequentially arranged first rolling rollers gradually decreases.

[0007] Specifically, the dry-process electrode preparation equipment also includes a material unloading device, which is arranged at the rolling device to put the material into the rolling device.

[0008] Specifically, the rolling equipment further includes a pre-pressing unit. The material enters the pre-pressing unit through the feeding equipment, and after preliminary calendering and forming, enters the rolling equipment for thinning.

[0009] Specifically, the pre-pressing device comprises at least two linear rollers arranged opposite to each other.

[0010] Specifically, the first pressing roller and / or the second pressing roller is provided with a heating part.

[0011] Specifically, the rotation speed ratio of the first pressing roller and the second pressing roller is in the range of 1:1-6:1.

[0012] The second aspect of the present invention discloses a method for preparing a dry electrode, which is characterized in that the material is subjected to fiberization treatment, and the material obtained by the fiberization treatment is rolled and thinned through the rolling gap of a plurality of rolling units arranged in sequence.

[0013] Specifically, the material and the current collector are rolled to obtain a dry-process electrode.

[0014] The advantages of the present invention are as follows:

[0015] (1) The rolling unit of the present invention comprises a first rolling roller and a second rolling roller arranged opposite to each other, wherein the first rolling roller is a convex arc roller, and the convex curvature of the plurality of convex arc rollers arranged in sequence gradually decreases. Such a convex structure reduces the rolling pressure required for rolling, ensures that the material is uniformly thinned during the calendering process, improves the quality and consistency of the film, avoids the problem of uneven thickness of the electrode film, and thus improves the performance of the product.

[0016] (2) The present invention first passes the material through the feeding device into the pre-pressing unit for preliminary calendering and then enters the roller pressing device for thinning. This multi-stage calendering treatment method helps to gradually optimize the morphology of the material at different stages, improve the control accuracy of the film forming process, ensure the uniformity and stability of the pole piece during the entire forming process, and improve the overall quality of the pole piece.

[0017] (3) The present invention provides a heating unit on the first pressing roller and / or the second pressing roller to ensure that the material maintains a suitable temperature during the calendering process to reduce viscosity and improve fluidity. At the same time, by adjusting the speed ratio of the first pressing roller and the second pressing roller, a flexible adjustment space is provided, which can be adjusted according to different materials and process requirements. Such a temperature control and speed adjustment design enables the equipment to have higher adaptability and flexibility, can meet the film forming requirements of various materials, and optimize production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a structural diagram of a rolling device in an embodiment of the present invention.

[0020] In the above drawings, the meanings of the reference numerals are as follows:

[0021] 1. The first pressing roller;

[0022] 2. The second pressure roller. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by technicians in the technical field to which the present invention belongs; the terms used in the specific implementation methods are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0025] In the description of the specific implementation methods of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0026] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present invention may be combined with other embodiments.

[0027] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0028] It should be noted that, for the convenience of description, in the following embodiments, all identical technical features are marked with the same symbols.

[0029] The electrode film forming method is generally divided into wet film forming process and dry film forming process. The traditional wet process requires the use of solvents and then heating and drying them. This process will affect production efficiency and increase production costs. In the dry process, no solvent is needed. The electrode can be obtained by hot pressing the fiberized binder, active material and current collector. Compared with the wet process, the dry process has higher production efficiency and is more environmentally friendly.

[0030] The dry process usually uses two pairs of linear rollers to extrude the material. The rollers need to apply a large roller pressure. Due to the large roller pressure, a large roller diameter is required to ensure its rigidity. However, the minimum rolling thickness of the roller is related to the roller diameter. A large roller diameter will limit the minimum thickness that can be rolled.

[0031] Therefore, the present invention proposes a dry-process electrode preparation device and method to improve the efficiency and quality of the electrode film forming process while reducing environmental impact and production costs.

[0032] The embodiments of the present invention will be described in more detail below through examples. It should be noted that the embodiments of the present invention are not limited to these examples.

[0033] like Figure 1 As shown, the present invention discloses a dry-process electrode preparation device, including a rolling device, the rolling device includes a plurality of rolling units arranged in sequence, the rolling unit includes a first pressing roller and a second pressing roller arranged opposite to each other, the first pressing roller is a convex arc roller, the diameter of the first pressing roller gradually decreases from the middle to both sides, and the curvature of the convex parts of the plurality of first pressing rollers arranged in sequence gradually decreases.

[0034] The first pressing roller is configured as a convex arc roller, and the curvature of the convex part of the first pressing roller in multiple rolling units arranged in sequence gradually decreases. This design ensures that the material can be thinned evenly and gradually during the entire film forming process, thereby improving the film forming quality and consistency of the electrode sheet. In addition, the convex arc roller requires less rolling pressure than the traditional straight roller.

[0035] In some embodiments, the dry-process electrode preparation equipment also includes a material unloading device, which is arranged at the rolling device and puts the fiberized material into the rolling device, thereby ensuring the continuity and stability of the film forming process and avoiding the problem of film quality caused by uneven material supply.

[0036] In specific applications, the material unloading equipment may be a vibrating feeder, a screw feeder or an impeller feeder, etc., all of which are common unloading equipment in the art and are only examples and not limitations.

[0037] In specific applications, the fiberization treatment method of the material can be selected from any one or a combination of two of air flow milling, high-speed stirring, mechanical fusion or twin-screw extrusion. The above are common fiberization methods in the art and are only examples and not limitations.

[0038] In some embodiments, the rolling equipment also includes a pre-pressing unit. The material enters the pre-pressing unit through the feeding equipment, and after preliminary calendering and forming, it enters the rolling equipment for thinning. This process allows the material to be preliminarily calendered and formed to prevent it from falling into powder before entering the rolling unit. This helps to improve the uniformity of the subsequent thinning process, reduce the internal stress of the pole piece, and improve the quality of the finished product.

[0039] In some embodiments, the pre-pressing device includes at least two relatively arranged linear rollers. This design provides a stable preliminary calendering process for the material, so that the material has a basic forming process before entering the thinning roller, laying a good foundation for the subsequent thinning process and ensuring the uniformity of the finished product.

[0040] In some embodiments, the first pressing roller and / or the second pressing roller is provided with a heating portion. This design allows the material to be heated during the calendering process, which is beneficial to improving the film forming effect and the uniformity of the electrode sheet.

[0041] In the above settings, the roughness of the first pressure roller and the second pressure roller can be selected to be the same or different. In practical applications, the roughness of the first pressure roller and the second pressure roller is preferably different, which helps to calender the electrode film in the rolling unit. The above settings are only examples and are not limiting.

[0042] In some embodiments, the speed ratio of the first pressing roller and the second pressing roller ranges from 1:1 to 6:1. This design allows the roller speed to be adjusted according to different materials and process requirements, optimizes the film forming effect, and improves the flexibility and adaptability of production.

[0043] In a specific application, the speed ratio of the first pressing roller and the second pressing roller arranged at the head is preferably 1.5:1, and the speed ratio of the first pressing roller and the second pressing roller arranged at the end is 3:1. The above values ​​are only examples and are not limiting.

[0044] The present invention also discloses a method for preparing a dry electrode sheet, wherein the material is subjected to fiberization treatment, and the material obtained by the fiberization treatment is thinned by rolling through the rolling gap of a plurality of rolling units arranged in sequence, and the material and the current collector are rolled to obtain a dry electrode sheet.

[0045] In the above preparation method, the current collector and the material can pass through the rolling gap at the same time to directly form a dry electrode sheet. At this time, the second pressing roller can be selected as a linear roller.

[0046] In the above preparation method, the material can also first pass through the rolling gap to form a dry self-supporting film, and then be compounded with the collector to prepare a dry electrode sheet. At this time, the second pressing roller can be selected as a roller with the same structure as the first pressing roller.

[0047] In the above preparation method, the material is usually obtained by dry-mixing the active substance, the conductive agent and the fiberizable binder, stirring them evenly and then subjecting them to a fiberization treatment. In some embodiments, there is no restriction on the order of adding the active substance, the conductive agent and the fiberizable binder. The binder can be added before the fiberization treatment, or it can be fiberized first and then added.

[0048] The dry electrode sheet prepared by the above method can be a dry positive electrode sheet or a dry negative electrode sheet. When preparing a dry positive electrode sheet, the materials can include positive electrode active material, conductive agent and binder. When preparing a dry negative electrode sheet, the materials can include negative electrode active material, conductive agent and binder.

[0049] In practical applications, the positive electrode active material can be selected to include any one or a combination of at least two of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium iron phosphate, lithium titanate or lithium-rich manganese-based materials. The above are all common positive electrode active materials in the field, which are only examples and not limitations.

[0050] In practical applications, the negative electrode active material may be selected to include any one of artificial graphite, natural graphite, microcrystalline graphite, soft carbon and hard carbon, or a combination of at least two of them. The above are common negative electrode active materials in the art, which are only examples and not limitations.

[0051] In practical applications, the conductive agent can be any one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers, or a combination of at least two of them. The above are all common conductive agents in the art, which are only examples and not limitations.

[0052] In practical applications, the binder can be selected from any one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), hydroxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylonitrile (PAN) or polyacrylate, or a combination of at least two thereof, preferably polytetrafluoroethylene or polyvinyl chloride. The above are all common binders in the art, which are only examples and not limitations.

[0053] In practical applications, aluminum foil may be selected as the positive electrode current collector, and copper foil may be selected as the negative electrode current collector. The above are common current collectors in the art and are only examples and not limitations.

[0054] Example 1

[0055] This embodiment provides a dry-process electrode preparation device including: a feeding device and a rolling device, wherein the rolling device includes a pre-pressing unit and a plurality of rolling units, wherein Figure 1 Each of the rolling units shown includes a first pressing roller and a second pressing roller that are correspondingly arranged.

[0056] Among them, the first pressing roller is a convex arc roller, and its diameter gradually decreases from the middle to the two sides, and the curvature of the convex parts of the first pressing rollers arranged in sequence gradually decreases. The material is gradually rolled and formed through the gap between the first pressing roller and the second pressing roller. Compared with the traditional straight roller, the convex arc roller needs to apply less rolling pressure on the material, and the thickness of the electrode film it can produce is thinner.

[0057] The unloading equipment can use a high-precision feeder to feed the material into the roller pressing equipment. The high-precision feeder can ensure the quality of the material film and realize the automation of the material film.

[0058] The pre-pressing unit can select two opposite linear rollers. The material is pre-pressed and formed by the two linear rollers before entering the roller pressing unit to ensure that the material can be initially formed, reduce the powdering and falling of the material, and ensure that the material can enter the roller pressing unit completely for calendering and thinning.

[0059] In a preferred embodiment, the first pressing roller and / or the second pressing roller is provided with a heating part. The heating part can be provided at the first pressing roller, or at the second pressing roller, or at both. The selection can be made according to needs and costs. The provision of the heating part can enable the material to be better rolled into a film, thereby ensuring the film forming quality of the electrode film.

[0060] Example 2

[0061] The present embodiment provides a method for preparing a dry electrode, comprising fiberizing a material, rolling the material obtained by the fiberization through the rolling gap of a plurality of rolling units arranged in sequence, gradually thinning the material into an electrode film in the rolling equipment, and rolling the electrode film and the current collector to obtain a dry electrode electrode.

[0062] The dry film forming equipment in this embodiment adopts the equipment in Example 1.

[0063] In some embodiments, the material is first formed into a dry electrode film by the above-mentioned equipment, and then combined with the current collector to form a dry electrode electrode, specifically:

[0064] A plurality of rolling units are arranged along the vertical direction, the first rolling roller is a convex arc roller of the above structure, the second rolling roller is also a convex arc roller of the above structure, the first rolling roller and the second rolling roller are arranged opposite to each other, the material includes electrode active material, conductive agent and binder, the material is put into the rolling gap between the first rolling roller and the second rolling roller, as the curvature of the convex part of the first rolling roller and the second rolling roller gradually decreases and becomes a straight roller, the material is gradually rolled into a pole piece film, and then the formed pole piece film is compounded onto the current collector to form a dry electrode pole piece.

[0065] In a preferred embodiment, some of the multiple rolling units are arranged in the vertical direction, and some are arranged in the horizontal direction. The first roller is a convex arc roller of the above structure, and the second roller is a linear roller. The first roller and the second roller are arranged oppositely. The material includes an electrode active material, a conductive agent and a binder. The material is put into the rolling gap between the first roller and the second roller. As the curvature of the convex part of the first roller gradually decreases and becomes a straight roller, the material is gradually rolled into an electrode film, and then the formed electrode film is composited onto the current collector to form a dry electrode. In this embodiment, the second roller is a linear roller, which is conducive to the material being pressed into a dry electrode film. It has good flatness, and the horizontal part of the rolling unit is arranged vertically, which is conducive to saving work space.

[0066] In a further preferred embodiment, some of the multiple rolling units are arranged in the vertical direction, and some are arranged in the horizontal direction. The first roller is a convex arc roller of the above structure, wherein the second roller in the rolling unit arranged in the vertical direction is also a convex arc roller of the above structure, and the second roller in the rolling unit arranged in the horizontal direction is a linear roller. The material includes an electrode active material, a conductive agent, and a binder. The material is put into the rolling gap between the first roller and the second roller, and the material is gradually rolled into an electrode film, and then the formed electrode film is compounded onto the current collector to form a dry electrode. In this embodiment, the second roller in the vertically arranged rolling unit adopts a convex arc roller, which is conducive to better rolling of the material, and the second roller in the horizontally arranged rolling unit adopts a linear roller, which is conducive to better flatness when the material is pressed into a dry electrode film. The horizontal part of the rolling unit is arranged vertically, which is conducive to saving work space.

[0067] Specifically, in this embodiment, the material is fed into the rolling equipment through the feeding equipment, and the material is gradually rolled into an electrode film. Generally speaking, when the material enters the first set of rollers, the initial rolling pressure is controlled at 0.1-1MPa to avoid excessive compression of the material, and then the rolling pressure is gradually increased, and the pressure is controlled at 10-20MPa in the middle roller section to ensure that the material is gradually formed. When the material is close to forming, the maximum rolling pressure is applied, which is usually controlled at 20-30MPa to make the electrode film reach the final thickness and density. Finally, the formed electrode film is compounded to the current collector to form a dry electrode electrode. During the compounding process, the pressure is controlled at 0.1-1MPa to ensure that the electrode film and the current collector are tightly combined to improve the composite quality. The temperature is controlled at 80-150°C during the compounding process, which can improve the bonding effect between the two and ensure the composite quality.

[0068] Example 3

[0069] The present embodiment provides a method for preparing a dry electrode sheet, including fiberizing a material, and rolling the fiberized material and a current collector through the rolling gap of a plurality of rolling units arranged in sequence, so that the material is gradually thinned and rolled onto the current collector to obtain a dry electrode sheet.

[0070] The dry film forming equipment in this embodiment adopts the equipment in Example 1.

[0071] In some embodiments, multiple rolling units are arranged in a horizontal direction, the first rolling roller is a convex arc roller of the above structure, the second rolling roller is a linear roller, the first rolling roller is arranged above the second rolling roller, wherein the current collector is arranged on the second rolling roller, the material includes an electrode active material, a conductive agent and a binder, the material is put into the pre-pressing unit through a feeding device to be pre-pressed and formed, and then enters the rolling unit together with the current collector, as the convex arc of the first rolling roller in the rolling unit gradually decreases, the material is gradually rolled and compounded onto the current collector to form a dry electrode sheet. In this embodiment, there is no need to first dry-press the material into a film and then compound it with the current collector, which can simplify the production process of the dry electrode sheet and realize the continuous production of the dry electrode sheet, thereby facilitating the improvement of the processing efficiency of the electrode sheet.

[0072] Specifically, in this embodiment, the material is fed into the roller pressing device through a feeding device, wherein the feeding device is a high-precision feeding device, and the material feeding speed can be set to 5-10kg / min, ensuring that the material is fed into the roller pressing device evenly and stably to avoid agglomeration and ensure the consistency of the film quality.

[0073] The material is rolled along the gap between the first roller and the second roller of the rolling unit. As the curvature of the convex part of the first roller gradually decreases, the material is gradually rolled and thinned. During the above rolling process, the material can be heated by the heating part, and the heating temperature can be controlled at 80-150°C, which can improve the efficiency of material film formation and ensure the quality of the electrode film.

[0074] It should be pointed out that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dry electrode preparation device, characterized in that: The roller pressing device comprises a plurality of roller units arranged in sequence; The pressing roller unit comprises a first pressing roller and a second pressing roller arranged opposite to each other, wherein the first pressing roller is a convex arc roller, the diameter of the first pressing roller gradually decreases from the middle to both sides, and the curvature of the convex parts of the plurality of first pressing rollers arranged in sequence gradually decreases.

2. The dry electrode preparation equipment according to claim 1, characterized in that: The dry-process electrode preparation equipment also includes a material unloading device, which is arranged at the rolling device and puts the material into the rolling device.

3. The dry electrode preparation equipment according to claim 2, characterized in that: The rolling equipment also includes a pre-pressing unit. The material enters the pre-pressing unit through the feeding equipment, and after preliminary calendering and forming, enters the rolling equipment for thinning.

4. The dry electrode preparation equipment according to claim 3, characterized in that: The pre-pressing device comprises at least two linear rollers arranged opposite to each other.

5. The dry electrode preparation equipment according to claim 1, characterized in that: The first pressing roller and / or the second pressing roller is provided with a heating part.

6. The dry electrode preparation equipment according to claim 1, characterized in that: The speed ratio of the first pressing roller to the second pressing roller ranges from 1:1 to 6:

1.

7. A method for preparing a dry electrode, characterized in that: The dry-process electrode preparation equipment according to any one of claims 1 to 6 is used to perform fiberization on the material, and the material obtained by the fiberization treatment is rolled and thinned through the rolling gaps of a plurality of rolling units arranged in sequence.

8. The method for preparing a dry electrode according to claim 7, characterized in that: The material and the current collector are rolled to obtain a dry-process electrode.

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