Dry-method pole piece preparation equipment and method

Abstract

The dry-method pole piece preparation equipment comprises rolling equipment, the rolling equipment comprises a plurality of pressing roller units which are arranged in sequence, each pressing roller unit comprises a first pressing roller and a second pressing roller which are oppositely arranged, the contact face between the first pressing roller and the second pressing roller is a working face, a material containing part is arranged on the first pressing roller, and the material containing part is arranged on the second pressing roller. A material containing space is formed between the material containing part and the working face, and the material containing spaces of the first pressing rollers which are sequentially arranged are gradually reduced, so that the production efficiency is remarkably improved, the production cost is reduced, the influence on the environment is reduced, and the overall performance and quality of products are improved.

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] In the preparation process of dry electrodes, the control of raw material dosage is a key link, which directly affects the thickness and quality of the electrode film, and thus affects the performance of the electrode. However, the traditional dry film-making process usually uses linear rollers and adopts an equal-width process for rolling in the length direction. This requires traditional dry film-making equipment to apply greater pressure, which easily causes the accumulation and waste of raw materials and the preparation process is also more cumbersome.

[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 significantly improves the overall performance and quality of the product, improves production efficiency, reduces production costs and reduces environmental impact. 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 roller units arranged in sequence, each roller unit includes a first roller and a second roller arranged opposite to each other, and the contact surface between the first roller and the second roller is a working surface, wherein a material containing portion is provided on the first roller, and a material containing space is formed between the material containing portion and the working surface, and the material containing space of the plurality of first rollers arranged in sequence gradually decreases.

[0007] Specifically, the first pressing roller is an arc-shaped roller, the cross section of the material containing portion along the axial direction of the first pressing roller is an arc surface, and the diameter of the first pressing roller gradually increases from the middle to both sides.

[0008] Specifically, the first pressing roller is a concave roller, and the cross-section of the material receiving portion along the axial direction of the first pressing roller is a triangle or a trapezoid.

[0009] Specifically, the radians of the arc surfaces of the plurality of first pressing rollers arranged sequentially gradually decrease.

[0010] Specifically, the angle between the cross-section of the material receiving portion of the plurality of first pressing rollers arranged in sequence and the central roller gradually decreases.

[0011] Specifically, the speed ratio of the first pressing roller to the second pressing roller ranges from 1 to 6.

[0012] Specifically, the dry-process electrode preparation equipment further includes a material unloading device, which is arranged at the rolling device and is used to place the material at the rolling device.

[0013] The second aspect of the present invention discloses a method for preparing a dry-process electrode, which is characterized in that the material is subjected to fiberization treatment, and the material obtained by the fiberization treatment is rolled through the rolling gap of a plurality of rolling units arranged in sequence.

[0014] Specifically, the material and the current collector are rolled to obtain a dry-process electrode.

[0015] The advantages of the present invention are as follows:

[0016] (1) The present invention is designed by a plurality of roller pressing units arranged in sequence, each unit comprising a first pressing roller and a second pressing roller arranged opposite to each other. The first pressing roller is provided with a material receiving portion, and as the material receiving space of the plurality of first pressing rollers is gradually reduced, it is ensured that during the film forming process, the material is gradually rolled into a thin film, thereby improving the uniformity and quality of the electrode film.

[0017] (2) The present invention designs arc-shaped rollers and concave rollers, and the cross-section of the material receiving portion along the axial direction is an arc surface, a triangle or a trapezoid. Through this design, the material can be more evenly distributed during the calendering process, reducing material accumulation and waste, while improving material utilization. In addition, the arc curvature and cross-sectional angle of the multiple rollers arranged in sequence gradually decrease, which helps the material to be gradually formed between different rolling units.

[0018] (3) The equipment in the present invention is equipped with a material unloading device to realize the automated operation of materials from unloading to calendering film forming, wherein the rotation speed of the roller pressing device can be flexibly adjusted according to different production requirements to ensure the stability and efficiency of the production process.

[0019] (4) The preparation method of the present invention can roll the material into a pole piece film and then combine it with the current collector to form a dry pole piece, or directly roll the current collector and the material into a dry pole piece, further reducing the production process and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] Figure 1 It is a structural diagram of a rolling device in an embodiment of the present invention.

[0022] In the above drawings, the meanings of the reference numerals are as follows:

[0023] 1. The first pressing roller;

[0024] 2. The second pressure roller. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] It should be noted that, for the convenience of description, in the following embodiments, all identical technical features are marked with the same symbols.

[0031] 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.

[0032] In the preparation process of dry electrodes, the control of raw material dosage is a key link, which directly affects the thickness and quality of the electrode film, and then affects the performance of the electrode. However, the traditional dry film making process usually uses linear rollers and adopts an equal-width process to carry out rolling in the length direction. In this case, the roller needs to apply greater pressure and it is easy to cause accumulation and waste of raw materials in the width direction.

[0033] Therefore, the present invention proposes a dry-process electrode preparation device and method, which significantly improves production efficiency, reduces production costs, reduces environmental impact, and improves the overall performance and quality of the product.

[0034] The embodiments of the present invention will be described in more detail below by way of examples. It should be noted that the embodiments of the present invention are not limited to these examples.

[0035] 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 roller units arranged in sequence, each roller unit includes a first roller and a second roller arranged opposite to each other, the contact surface between the first roller and the second roller is a working surface, wherein a material accommodating portion is provided on the first roller, a material accommodating space is formed between the material accommodating portion and the working surface, and the material accommodating space of the plurality of first rollers arranged in sequence gradually decreases.

[0036] Through the above arrangement, the material holding part has the functions of pre-pressing and storing materials, and has low requirements for the control of material feeding accuracy, which will not cause material accumulation and waste. The material holding space is gradually reduced by multiple pressing rollers, so that the material is gradually thinned and formed during the calendering process, thereby improving the uniformity and quality of the electrode sheet.

[0037] In some embodiments, the first pressing roller is an arc-shaped roller, and the cross-section of the material receiving portion along the axial direction of the first pressing roller is an arc surface. The diameter of the first pressing roller gradually increases from the middle to both sides. This helps to distribute the material more evenly during the calendering process, reduce material accumulation and waste, and ensure that the thickness and quality of the electrode are consistent.

[0038] In some embodiments, the first pressing roller is a concave roller, and the cross-section of the material receiving portion along the axial direction of the first pressing roller is triangular or trapezoidal, which helps to optimize the distribution of the material during the calendering process, improve material utilization, and further reduce material accumulation.

[0039] In some embodiments, the radian of the camber of the plurality of first pressing rollers arranged in sequence gradually decreases. The advantage of this design is that the camber of the camber of the pressing roller gradually decreases, and the material is gradually squeezed to both sides. Since the sheeting area is small, the pressure requirement on the pressing roller is not high, which can help control the material flow more evenly, ensure that the material gradually becomes thinner during the calendering process, and form a uniform electrode film.

[0040] In some embodiments, the angle between the cross-section of the material receiving portion of the plurality of first pressing rollers arranged in sequence and the center roller gradually decreases, further optimizing the distribution and flow of the material during the calendering process, reducing material waste, and improving the film forming quality of the electrode.

[0041] In some embodiments, the speed ratio of the first pressing roller and the second pressing roller is in the range of 1:1-6:1. By adjusting the speed ratio, the calendering speed and pressure can be flexibly controlled to ensure the stability and efficiency of the film forming process.

[0042] In practical applications, the speed ratio between the first pressing roller and the second pressing roller can be selected as 1:1, 2:1, 3:1, 4:1, 5:1, or 6:1. The above data are only examples and are not limiting.

[0043] In some embodiments, the dry electrode preparation equipment also includes a material unloading device, which is arranged at the rolling device and is used to place the material on the rolling device to ensure the stability and uniformity of the raw material input and improve the efficiency and effect of the calendering process.

[0044] In practical 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.

[0045] 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 rolled 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.

[0046] In the above preparation method, 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] Example 1

[0056] This embodiment provides a dry electrode preparation device, which includes a feeding device and a rolling device, such as Figure 1 As shown, the rolling device includes a plurality of rolling units arranged in sequence, each of which includes a first pressing roller 1 and a second pressing roller 2 arranged opposite to each other, and the contact surface between the first pressing roller 1 and the second pressing roller 2 is a working surface.

[0057] Among them, the unloading equipment is used to put the material into the rolling equipment, and the first pressing roller 1 and the second pressing roller 2 in the rolling unit of the rolling equipment are used to gradually roll and shape the material that falls into the material holding space formed by the first pressing roller 1 and the second pressing roller 2. The material can be initially rolled in the material holding space formed by the first pressing roller 1 and the second pressing roller 2 of the first rolling unit, and then transported to the material holding space formed by the first pressing roller 1 and the second pressing roller 2 of the next rolling unit to be rolled again until the material is rolled and thinned into shape.

[0058] In a preferred embodiment, Figure 1 As shown, the first pressing roller 1 is an arc-shaped roller, and the diameter of the first pressing roller 1 gradually increases from the middle to both sides. The first pressing roller 1 is provided with a material receiving portion, which forms a material receiving space with the working surface. The arc curvature of the arc surface of the first pressing rollers 1 arranged in sequence gradually decreases until it becomes a straight roller. As the arc curvature of the first pressing roller 1 gradually decreases, the material is gradually rolled and formed. The material receiving portion has the functions of pre-pressing and storing materials, and the requirements for the precision control of the material discharge are relatively low, and the accumulation and waste of materials will not be caused. In addition, the arc curvature of the first pressing roller 1 gradually decreases. Since the material sheeting area is small, the pressure requirements for the pressing roller are not high.

[0059] In some optional embodiments, the first pressing roller 1 may also be a concave roller, and the material holding portion of the first pressing roller 1 has a triangular or trapezoidal cross-section along the axial direction of the first pressing roller 1. The first pressing roller 1 is provided with a material holding portion to form a material holding space with the working surface. The angle between the cross-section of the material holding portions of the multiple first pressing rollers 1 arranged in sequence and the working surface gradually decreases until they become a straight roller. This embodiment has the same effect as the above-mentioned preferred method.

[0060] In some optional embodiments, the structure of the second pressing roller 2 is not limited, and it can be selected as a linear roller according to needs, or it can be selected as a roller with the same structure as the first pressing roller 1.

[0061] In some optional embodiments, the diameters of the first pressing roller 1 and the second pressing roller 2 are not limited.

[0062] In some preferred embodiments, the diameter of the first pressing roller 1 is the same as the diameter of the second pressing roller 2 , or the diameter of the first pressing roller 1 is greater than the diameter of the second pressing roller 2 .

[0063] The rolling device comprises a plurality of rolling units arranged in sequence.

[0064] In some preferred embodiments, the plurality of rolling units are arranged horizontally or vertically, such as Figure 1 As shown, the plurality of rolling units are arranged horizontally.

[0065] In a further preferred embodiment, some rolling units are arranged vertically, and other rolling units are arranged horizontally, and guide rollers can be arranged between the vertically arranged rolling units and the horizontally arranged rolling units. Compared with all horizontally arranged or all vertically arranged, it is beneficial to improve space utilization and facilitate processing.

[0066] Example 2

[0067] This embodiment provides a method for preparing a dry electrode sheet, comprising feeding a fiberized material into a rolling device through a feeding device for rolling, gradually thinning the material in the rolling device, and rolling the material and a current collector to obtain a dry electrode sheet.

[0068] The dry film forming equipment in this embodiment adopts the equipment in Example 1.

[0069] In some embodiments, the material is first formed into a dry self-supporting film through the above-mentioned equipment, and then combined with the current collector to form a dry electrode plate, specifically:

[0070] A plurality of rolling units are arranged along the vertical direction, the first rolling roller is an arc-shaped roller of the above structure, the second rolling roller is also an arc-shaped 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 material containing part of the first rolling roller and the second rolling roller arranged sequentially gradually decreases, the material is gradually rolled into a self-supporting film, and then the formed self-supporting film is compounded onto the current collector to form a dry electrode sheet.

[0071] 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 rolling roller is an arc roller of the above structure, and the second rolling roller is a linear roller. 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 material containing parts of the first rolling roller and the second rolling roller arranged in sequence gradually decrease, the material is gradually rolled into a self-supporting film, and then the formed self-supporting film is compounded onto the current collector to form a dry electrode sheet. In this embodiment, the second rolling roller adopts a linear roller, which is beneficial for the material to have better flatness when being pressed into a dry electrode sheet film. The horizontal part of the rolling unit is partially and the vertical part is arranged vertically, which is beneficial for saving working space.

[0072] In a further preferred embodiment, some of the multiple rolling units are arranged along the vertical direction, and some of the rolling units are arranged along the horizontal direction. The first roller is an arc roller of the above structure, wherein the second roller in the rolling unit arranged along the vertical direction is also an arc roller of the above structure, and the second roller in the rolling unit arranged along the horizontal direction is a linear roller. The first roller and the second roller are arranged oppositely, and 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 material receiving parts of the first roller and the second roller arranged in sequence gradually decrease, the material is gradually rolled into a self-supporting film, and then the formed self-supporting film is composited onto the current collector to form a dry electrode sheet. In this embodiment, the second roller in the vertically arranged rolling unit adopts an 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 the material being pressed into a dry electrode sheet film. It has good flatness, and the horizontal part of the rolling unit is arranged vertically, which is conducive to saving work space.

[0073] In some embodiments, the current collector and the material are simultaneously passed through the roller press gap to directly form a dry electrode sheet, specifically:

[0074] Multiple rolling units are arranged in the horizontal direction, the first rolling roller is an arc-shaped 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 material holding part, the material holding part of the first rolling roller arranged in sequence gradually decreases, and the material is gradually rolled and compounded on 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.

[0075] 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; Each pressing roller unit includes a first pressing roller and a second pressing roller arranged opposite to each other, wherein the contact surface between the first pressing roller and the second pressing roller is a working surface, wherein a material accommodating portion is provided on the first pressing roller, and a material accommodating space is formed between the material accommodating portion and the working surface, and the material accommodating space of multiple first pressing rollers arranged in sequence gradually decreases.

2. The dry electrode preparation equipment according to claim 1, characterized in that: The first pressing roller is an arc-shaped roller, the cross section of the material containing portion along the axial direction of the first pressing roller is an arc surface, and the diameter of the first pressing roller gradually increases from the middle to both sides.

3. The dry electrode preparation equipment according to claim 1, characterized in that: The first pressing roller is a concave roller, and the cross section of the material receiving portion along the axial direction of the first pressing roller is a triangle or a trapezoid.

4. The dry electrode preparation equipment according to claim 2, characterized in that: The radians of the cambered surfaces of the plurality of first pressing rollers arranged sequentially gradually decrease.

5. The dry electrode preparation equipment according to claim 3, characterized in that: The included angles between the cross-sections of the material receiving parts of the plurality of first pressing rollers arranged in sequence and the central roller gradually decrease.

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 to 6.

7. The dry electrode preparation equipment according to claim 1, characterized in that: It also includes a material unloading device, which is arranged at the roller pressing device and is used to place the material onto the roller pressing device.

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

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

Images