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 at least one rolling unit, each rolling unit comprises a center roller and a plurality of pressing rollers sequentially arranged in the circumferential direction of the center roller, the contact faces between the center roller and the pressing rollers are working faces, and material containing parts are arranged on the pressing rollers; a material containing space is formed between the material containing part and the working face, and the material containing spaces of the multiple sequentially-arranged pressing rollers are gradually reduced, 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 methods are mainly divided into wet film forming process and dry film forming process. The traditional wet process requires the use of solvents and removes the solvents by heating and drying. This process not only affects production efficiency, but also increases production costs. In contrast, the dry process does not require the use of solvents. The electrode is directly made by hot pressing the fiberized binder, active material and current collector. This method not only improves production efficiency, but is also more environmentally friendly.

[0003] In the preparation process of dry electrodes, the control of raw material dosage is crucial because it directly affects the thickness and quality of the electrode film, thereby affecting the overall performance of the electrode. However, the traditional dry film making process usually uses linear rollers and uses an equal-width process to calender in the length direction. In this case, the rollers must apply greater pressure, and it is easy to cause accumulation and waste of raw materials in the width direction.

[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, and 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 the rolling device including at least one rolling unit, the rolling unit including: a center roller and a plurality of pressing rollers arranged in sequence along the circumference of the center roller, the contact surface between the center roller and the pressing roller is a working surface, the pressing roller is provided with a material containing part, and a material containing space is formed between the material containing part and the working surface, wherein the material containing space of the plurality of pressing rollers arranged in sequence gradually decreases.

[0007] Specifically, the pressing roller is an arc-shaped roller, and the cross-section of the material containing portion along the axial direction of the pressing roller is an arc surface.

[0008] Optionally, the pressing roller is a concave roller, and the cross-section of the material receiving portion along the axial direction of the pressing roller is triangular or trapezoidal.

[0009] Specifically, the radians of the arc surfaces of the plurality of pressure rollers arranged sequentially gradually decrease until they become straight rollers.

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

[0011] Specifically, the center roller is a straight roller, and the diameter of the center roller is larger than the diameter of the pressure roller.

[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] Specifically, the dry-process electrode preparation equipment also includes an electrode substrate receiving and releasing device, and the electrode substrate is a current collector.

[0014] Specifically, the rolling device is provided on at least one side of the current collector conveying path of the pole piece substrate receiving and placing device.

[0015] The second aspect of the present invention discloses a method for preparing a dry-process electrode sheet, which is characterized in that the material after fiberization treatment is put into a rolling device through a feeding device for calendering. After the material passes through the rolling gap between the center roller and the sequentially arranged pressing rollers along the circumference of the center roller, it is gradually thinned and formed to obtain a electrode sheet film, and the electrode sheet film and the current collector are compounded to obtain a dry-process electrode sheet.

[0016] The advantages of the present invention are as follows:

[0017] (1) The roller pressing equipment of the present invention is designed with a material accommodation space that is gradually reduced by multiple rollers, ensuring that the raw materials are gradually thinned and formed during the film forming process, thereby improving the uniformity and quality of the electrode film. This progressive calendering method avoids the problems of pressure concentration and uneven thickness caused by a single calendering.

[0018] (2) The design of the arc roller and the concave roller in the roller pressing device of the present invention makes the cross section of the material receiving part be an arc surface, a triangle or a trapezoid, and reduces the accumulation and waste of raw materials by accurately controlling the material distribution. At the same time, the design of gradually decreasing arc enables the pressing roller to distribute and control the material more effectively.

[0019] (3) The present invention is also provided with material unloading equipment and pole piece substrate receiving and releasing equipment, which realizes the full process automation operation from material unloading, pole piece film rolling, and pole piece forming, ensuring the efficiency and stability of the pole piece forming process. 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 1It is a structural diagram of a dry-process electrode preparation device disclosed in the present invention;

[0022] Figure 2 This is a horizontal arrangement structure diagram of a rolling unit according to Embodiment 1 of the present invention;

[0023] Figure 3 This is a vertical structural diagram of the rolling unit of Example 1 of the present invention.

[0024] In the above drawings, the meanings of the reference numerals are as follows:

[0025] 1. Cutting equipment;

[0026] 2. Pressing roller;

[0027] 3. Center roller;

[0028] 4. The first rolling unit;

[0029] 5. The second rolling unit. DETAILED DESCRIPTION

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] It should be noted that, for the convenience of description, in the following embodiments, all identical technical features are marked with the same symbols.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] like Figure 1As shown, the present invention discloses a dry-process electrode preparation device, including a rolling device, the rolling device includes at least one rolling unit, the rolling unit includes: a central roller and a plurality of pressing rollers arranged in sequence along the circumference of the central roller, the contact surface between the central roller and the pressing roller is a working surface, a material accommodating portion is arranged on the pressing roller, a material accommodating space is formed between the material accommodating portion and the working surface, wherein the material accommodating space of the plurality of pressing rollers arranged in sequence gradually decreases.

[0041] Through the above arrangement, the material holding part has the functions of pre-pressing and storing materials, and has low requirements for the precision control of material feeding, 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. Multiple pressing rollers can be distributed at intervals along the circumference of the center roller, and multiple pressing rollers can also be distributed continuously along the circumference of the center roller.

[0042] In some embodiments, the pressing roller is an arc roller, and the cross-section of the material holding portion along the axis of the pressing roller is an arc surface, wherein the arc roller can be an arc roller with a constant diameter and an overall curved shape, or the arc roller can be an arc roller with a diameter that gradually increases from the middle to both sides and is concave in the middle. It is only necessary to ensure that the cross-section of the material holding portion is an arc surface. This helps to distribute the material more evenly during the calendering process, reduce material accumulation and waste, and ensure the consistency of the thickness and quality of the electrode.

[0043] In some embodiments, the pressing roller is a concave roller, and the cross-section of the material receiving portion along the axis of the 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.

[0044] In some embodiments, the radian of the camber of the plurality of pressure rollers arranged in sequence gradually decreases until they become straight rollers. The advantage of this design is that the camber of the camber of the pressure roller gradually decreases, the material is gradually squeezed and thinned, and since the sheeting area is small, the pressure requirement on the pressure roller is not high, which can help control the material flow more evenly, ensure that the material is gradually thinned during the calendering process, and form a uniform electrode film.

[0045] In some embodiments, the angle between the cross-section of the material holding portion of the plurality of pressure rollers arranged in sequence and the center roller gradually decreases until they become straight rollers, 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.

[0046] In some embodiments, the center roller is a straight roller, and the diameter of the center roller is larger than the diameter of the pressing roller. This design can provide a more stable calendering basis, ensure that the material can be evenly distributed and formed during the calendering process, and improve the film quality of the electrode.

[0047] In some preferred embodiments, the diameter of the center roller ranges from 100 to 2000, and the diameter of the pressure roller ranges from 50 to 800.

[0048] 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.

[0049] In some embodiments, the dry-process electrode preparation equipment also includes an electrode substrate receiving and releasing device. The electrode substrate is a current collector and is used for processing and conveying the current collector to ensure the continuous supply of the electrode substrate and the collection of finished products during the calendering process, thereby improving the automation level and production efficiency of the production line.

[0050] In some embodiments, at least one side of the current collector conveying path of the pole piece substrate receiving and placing device is provided with a rolling device, which can directly compound the pole piece film with the current collector after processing, which is beneficial to improving the processing efficiency of the pole piece.

[0051] In specific applications, the pole piece substrate receiving and releasing device can be set according to the actual needs of the current collector and the pole piece film. If the pole piece film is only set on one side of the current collector, the rolling device can be only set on one side of the pole piece substrate receiving and releasing device. If the pole piece film is set on both sides of the current collector, the rolling device can also be two sets respectively set on both sides of the pole piece substrate receiving and releasing device. The rolling devices on both sides can produce pole piece films at the same time, and the produced pole piece films can be bonded with the current collector at the same time, thereby improving production efficiency.

[0052] The present invention also discloses a method for preparing a dry-process electrode sheet. The material after fiberization treatment is put into a rolling device through a feeding device for calendering. The material passes through the rolling gap between the center roller and the sequentially arranged pressing rollers along the circumference of the center roller, and is gradually thinned and formed to obtain a electrode sheet film. The electrode sheet film and the current collector are compounded to obtain a dry-process electrode sheet.

[0053] In the above preparation method, the material is usually obtained by dry-mixing and stirring the active substance, the conductive agent and the fiberizable binder evenly and then performing a fiberization treatment. In some embodiments, the order of adding the active substance, the conductive agent and the fiberizable binder is not limited. The binder can be added and then fiberized, or it can be fiberized first and then added. Then the material is obtained and put into the rolling equipment through the feeding equipment. The equipment can be used for dry positive electrode sheet film formation, and can also be used for dry negative electrode sheet film formation.

[0054] In some embodiments, the active material may be a positive electrode active material or a negative electrode active material. When the electrode active material is a positive electrode active material, it may 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 phosphate, lithium iron phosphate, lithium titanate, or lithium-rich manganese-based materials. The above are all common positive electrode active materials in the art, which are only examples and not limitations.

[0055] When the electrode active material is a negative electrode active material, it can be selected from any one or a combination of at least two of artificial graphite, natural graphite, microcrystalline graphite, soft carbon and hard carbon. The above are common negative electrode active materials in the art, which are only examples and not limitations.

[0056] In some embodiments, the conductive agent includes any one or a combination of at least two of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers. The above are all common conductive agents in the art, which are only examples and not limitations.

[0057] In some embodiments, the binder includes 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.

[0058] Example 1

[0059] This embodiment provides a rolling device in a dry electrode preparation device, such as Figure 1 As shown, the rolling device includes at least one rolling unit, which includes a central roller 3 and a plurality of pressing rollers 2 sequentially arranged along the circumference of the central roller 3 .

[0060] Among them, the center roller 3 and the pressure roller 2 are used to gradually roll the material falling into the material holding space formed by the two to form an electrode film. Multiple pressure rollers 2 are arranged circumferentially around the center roller 3 and the material holding space formed by them gradually decreases. The material can be initially rolled in the material holding space formed by the first pressure roller 2 and the center roller 3 and transported to the material holding space formed by the next pressure roller 2 and the center roller 3 as the center roller rotates until the material is rolled and thinned into an electrode film of the target thickness.

[0061] In a preferred embodiment, Figure 1As shown, the pressing roller 2 is an arc-shaped roller, and the material receiving part of the pressing roller 2 has an arc surface in the cross section along the axial direction of the pressing roller 2 and forms a material receiving space with the center roller 3. The arc curvature of the arc surfaces of the multiple pressing rollers 2 arranged in sequence gradually decreases until they become straight rollers. As the arc curvature of the pressing roller 2 gradually decreases, the material is gradually rolled into an electrode film. The material receiving part has the functions of pre-pressing and storing materials, and the requirements for the precision control of material feeding are relatively low, which will not cause the accumulation and waste of materials. In addition, the arc curvature of the pressing roller gradually decreases. Since the material sheeting area is small, the pressure requirements for the pressing roller are not high.

[0062] In some optional embodiments, the pressing roller 2 may also be a concave roller, the material holding portion of the pressing roller 2 has a triangular or trapezoidal cross-section along the axial direction of the pressing roller 2 and forms a material holding space with the center roller 3, and the angle between the cross-section of the material holding portions of the plurality of pressing rollers 2 arranged in sequence and the center roller 3 gradually decreases until it becomes a straight roller.

[0063] In a preferred embodiment, the center roller 3 is a straight roller, and the diameter of the center roller 3 is larger than the diameter of the pressing roller 2. The center roller 3 with a larger diameter can provide a more stable calendering foundation, ensure that the material can be evenly distributed and formed during the calendering process, and improve the film forming quality of the pole piece.

[0064] The rolling device includes at least one rolling unit as described above. In some embodiments, the number of the rolling unit is one.

[0065] In some preferred embodiments, there are multiple rolling units, and the multiple rolling units are arranged horizontally or vertically, such as Figure 2 As shown, the rolling device includes two rolling units, and the two rolling units are both arranged horizontally. Figure 3 As shown, the rolling device includes two rolling units, and the two rolling units are vertically spaced apart.

[0066] In a further preferred embodiment, there are multiple roller pressing units, some of which are arranged vertically, and other roller pressing units are arranged horizontally, and guide rollers can be arranged between the vertically arranged roller pressing units and the horizontally arranged roller pressing units. Compared with all horizontally arranged or all vertically arranged, it is beneficial to improve space utilization and facilitate processing.

[0067] Example 2

[0068] This embodiment provides a dry electrode preparation device, including a material feeding device, a rolling device, and an electrode substrate receiving and releasing device. The material feeding device is used to feed the material into the rolling device, the rolling device is used to calender the material to form an electrode film, and the electrode substrate receiving and releasing device is used to transport the current collector to compound the electrode film to form a dry electrode electrode. The rolling device in this embodiment adopts the rolling device in Example 1.

[0069] In some optional embodiments, the rolling equipment is arranged on at least one side of the pole piece substrate receiving and releasing equipment. After the material is put into the rolling equipment through the feeding equipment and rolled into a pole piece film, it can be formed into an electrode pole piece after single-sided rolling with the current collector through the pole piece substrate receiving and releasing equipment. This embodiment can be selected when only a single-sided pole piece film is required.

[0070] In some preferred embodiments, the rolling equipment can be arranged on both sides of the electrode substrate receiving and placing equipment. After the materials on both sides form the electrode film, they can be compounded with the two sides of the current collector to form an electrode electrode, thereby improving the processing efficiency of the electrode.

[0071] Example 3

[0072] The present embodiment provides a method for preparing a dry-process electrode, comprising feeding a fiberized material into a rolling device through a feeding device for rolling, gradually thinning the material in the rolling device to form an electrode film, and compounding the obtained electrode film and a current collector to obtain a dry-process electrode electrode. The dry-process film-forming equipment in the present embodiment adopts the equipment in Example 2.

[0073] Specifically, in this embodiment, the material is fed into the material holding portion of the pressure roller of the rolling equipment through the unloading equipment, and the material is rolled at the material holding portion of the pressure roller along the circumference of the center roller of the rolling equipment. As the material holding space of the pressure roller arranged along the circumference of the center roller gradually decreases, the material is gradually rolled into an electrode film. Generally speaking, when the material enters the first group of pressure 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 controlled at 10-20MPa in the middle pressure roller section to ensure that the material is gradually formed. Finally, when the material is close to forming, the maximum rolling pressure is applied, usually controlled at 20-30MPa, so that the electrode reaches the final thickness and density.

[0074] Finally, the formed electrode film is compounded onto the current collector through the electrode substrate taking-up and releasing equipment 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. During the compounding process, the temperature is controlled at 80-150℃ to improve the bonding effect and ensure the composite quality.

[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: comprising a rolling device, the rolling device comprising at least one rolling unit; The rolling unit includes: a central roller and a plurality of pressing rollers arranged in sequence along the circumference of the central roller, the contact surface between the central roller and the pressing roller is a working surface, a material containing portion is provided on the pressing roller, a material containing space is formed between the material containing portion and the working surface, wherein the material containing space of the plurality of pressing rollers arranged in sequence gradually decreases.

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

3. The dry electrode preparation equipment according to claim 1, characterized in that: The pressing roller is a concave roller, and the cross section of the material receiving portion along the axial direction of the 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 arc surfaces of the plurality of pressure rollers arranged sequentially gradually decrease until they become straight rollers.

5. The dry electrode preparation equipment according to claim 3, characterized in that: The angle between the cross-section of the material receiving portion of the plurality of pressure rollers arranged in sequence and the central roller gradually decreases until they become straight rollers.

6. The dry electrode preparation equipment according to claim 1, characterized in that: The center roller is a straight roller, and the diameter of the center roller is larger than the diameter of the pressure roller.

7. 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 is used to place the material at the rolling device.

8. The dry electrode preparation equipment according to claim 1, characterized in that: The dry-process electrode preparation equipment also includes an electrode substrate receiving and releasing device, and the electrode substrate is a current collector.

9. The dry electrode preparation equipment according to claim 8, characterized in that: The rolling device is provided on at least one side of the current collector conveying path of the pole piece substrate receiving and placing device.

10. A method for preparing a dry electrode, characterized in that: By using the dry electrode preparation equipment described in any one of claims 1 to 9, the material after fiberization treatment is put into the rolling equipment through the feeding equipment for calendering, and the material passes through the rolling gap between the center roller and the pressing rollers arranged in sequence along the circumference of the center roller, and is gradually thinned and formed to obtain a electrode film, and the electrode film and the current collector are compounded to obtain a dry electrode electrode.

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