Membrane preparation device, pole piece manufacturing equipment and membrane preparation method

Abstract

The application provides a membrane preparation device, a pole piece manufacturing equipment and a membrane preparation method. The membrane preparation device comprises a mixing mechanism, a first feeding mechanism, a second feeding mechanism and an extrusion die. The first feeding mechanism is used for adding a powder mixture containing a powder and a first binder into the mixing mechanism. The second feeding mechanism is used for adding a solution containing a second binder into the mixing mechanism. The mixing mechanism is used for mixing the powder mixture and the solution. The extrusion die is connected to the discharge end of the mixing mechanism and is used for extruding a membrane. When the membrane preparation device is applied to the preparation of an active material layer membrane of a pole piece, the mixing uniformity and the distribution uniformity of the active material mixture can be effectively improved, and the proportion of the active material can be increased. Therefore, the production quality of the pole piece is effectively improved, and the energy density of the battery is effectively improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery manufacturing, in particular to a diaphragm preparation device, a pole piece manufacturing equipment and a diaphragm preparation method. BACKGROUND

[0002] Energy saving and emission reduction is the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their energy saving and environmental protection advantages. For electric vehicles, battery technology is an important factor for their development.

[0003] In battery production, how to improve the production quality and energy density of the battery is a problem to be solved. SUMMARY

[0004] The application provides a diaphragm preparation device, a pole piece manufacturing equipment and a diaphragm preparation method, which can effectively improve the production quality and energy density of the battery.

[0005] In a first aspect, the application provides a diaphragm preparation device, comprising a mixing mechanism, a first feeding mechanism, a second feeding mechanism and an extrusion die head, the first feeding mechanism is used for adding a powder mixture containing powder and a first binder to the mixing mechanism, the second feeding mechanism is used for adding a solution containing a second binder to the mixing mechanism, the mixing mechanism is used for mixing the powder mixture and the solution, and the extrusion die head is connected to the discharge end of the mixing mechanism and is used for extruding a diaphragm.

[0006] The diaphragm preparation device of the application can realize the purpose of directly mixing the powder mixture and the solvent and then extruding the diaphragm. The first feeding mechanism and the second feeding mechanism are designed to facilitate classified feeding into the mixing mechanism. When the diaphragm preparation device is applied to the preparation of the active material layer diaphragm of the pole piece, the first feeding mechanism can be used to add a powder mixture containing electrode active material powder and a first binder which is not easy to dissolve in the solvent or has poor solubility in the solvent to the mixing mechanism, and the second feeding mechanism can be used to add a solution containing a second binder to the mixing mechanism. The mixing mechanism mixes the powder mixture and the solution. The first type of binder is fiberized to form a reticular structure, and the electrode active material and other raw materials are bundled and fixed in the binder fiber grid to form an active material mixture with a muscle net structure. The solution containing the second type of binder effectively increases the flexibility and adhesion of the active material mixture, thereby forming a lump-shaped active material mixture with certain viscosity and plasticity. Then, the active material mixture is extruded into an active material diaphragm by the extrusion die head.

[0007] In one aspect, the technical scheme of the present application mixes the first binder which is not easy to dissolve in the solvent or aqueous solution and the powder to form a powder mixture in advance, which can avoid the problem of agglomeration and poor dispersion of the first binder after being directly mixed into the solution due to its poor solubility, thereby improving the dispersion uniformity of the first binder in the active material mixture. In another aspect, the technical scheme of the present application dissolves the second binder which plays a binding role in the solvent to form a solution, and then mixes the solution with the powder mixture, which can effectively ensure the dispersion uniformity of the second binder in the active material mixture and fully exert the flexible binding effect of the second binder on the active material mixture. In still another aspect, compared with the pure dry method of preparing the film sheet without solvent, the technical scheme of the present application adds the solution to the mixture through the second feeding mechanism, thereby effectively improving the loose structure of the active material mixture and improving the plasticity and ductility of the active material mixture, thereby improving the compactibility of the film sheet, and further improving the volume ratio of the active material of the pole piece. Moreover, the addition of the solution can effectively reduce the demand for the first binder, thereby being conducive to improving the content ratio of the active material and effectively improving the energy density of the battery by increasing the ratio of the active material. In general, the film sheet preparation device can effectively improve the mixing uniformity and component distribution uniformity of the active material mixture, and is conducive to improving the ratio of the active material, thereby effectively improving the production quality of the pole piece and the energy density of the battery.

[0008] According to some embodiments of the present application, the extrusion die is directly connected to the discharge end of the mixing mechanism.

[0009] In the above technical scheme, the extrusion die is directly installed at the discharge end of the mixing mechanism, and the overall film sheet preparation device integrates mixing and extrusion molding, which has strong structural integration. Compared with the structure in which the material mixing and extrusion molding are separately arranged, the technical scheme of the present application effectively reduces the material transfer time and the repeated shearing and conveying time of the material, simplifies the production process, and improves the production efficiency of the battery pole piece. At the same time, the production equipment demand is effectively reduced, the manufacturing cost is saved, and the practicality is strong and the economic benefits are outstanding.

[0010] According to some embodiments of the present application, the mixing mechanism is a double screw machine.

[0011] In the above technical scheme, the mixing mechanism is a double screw machine, which can sufficiently mix, shear and knead the powder mixture and the solution, achieve the purpose of uniform mixing of the powder mixture and the solution in the double screw machine, and provide extrusion power for the extrusion molding of the film sheet by conveying and building pressure during the mixing of the material, so that the mixed mixture after mixing can be extruded into a film sheet through the extrusion die.

[0012] According to some embodiments of the present application, the screw of the double screw machine is composed of alternately arranged banbury rotor elements and threaded conveying elements.

[0013] In the technical solution, the screw of the double screw machine is composed of the interlaced arrangement of the mixing rotor element and the threaded conveying element, the threaded conveying element performs material transmission, the mixing rotor element performs sufficient dispersion, shearing and kneading on the material to sufficiently balance the shearing mixing and conveying capacity of the diaphragm preparation device; at the same time, the shearing force of the mixing rotor element is relatively mild, which can effectively reduce the risk of the active electrode particle morphology being broken due to over-shearing, thereby reducing the risk of battery gas production and low initial efficiency of the battery; and the mild shearing force of the mixing rotor element can make the binder be fiberized without destroying the fiber structure, thereby effectively reducing the risk of the binder being disabled due to over-shearing.

[0014] According to some embodiments of the present application, the width of the screw flight of the mixing rotor element is d, the outer diameter of the screw is D, and 0.02D≤d≤0.15D, preferably 0.04D≤d≤0.1D.

[0015] The mixing rotor element is usually used in cooperation with a pair of elements in mirror image relationship, the screw flights of the mixing rotor element are surrounded to form a containing space for containing the material, and the material in the containing space is mainly subjected to shearing and kneading in the containing space and the slit between the screw flight and the inner wall of the barrel of the double screw machine, so that the material is uniformly mixed.

[0016] If the width of the screw flight of the mixing rotor element is too wide, the free volume of the containing space is small, and at the same time, the resistance of the channel formed by the space between the screw flight and the barrel wall increases, the rate of the material moving under the shearing action decreases, the number of times of shearing of the material also decreases, and the material is prone to be insufficiently mixed; on the contrary, if the width of the screw flight of the mixing rotor element is too small, the free volume of the containing space increases, the material is prone to be accumulated in the containing space, and at the same time, the shearing rate of the material passing through the space between the screw flight and the barrel wall increases, the number of times of shearing also increases, and the material is prone to be over-sheared and the structure of the binder is damaged.

[0017] In the technical solution, the ratio of the width of the screw flight of the mixing rotor element to the outer diameter of the screw is set to be between 0.02 and 0.15, which can effectively ensure that the material is sufficiently and uniformly mixed while avoiding over-shearing, thereby effectively ensuring the production quality of the diaphragm and further effectively ensuring the production quality of the battery.

[0018] According to some embodiments of the present application, the helix angle of the screw flight of the mixing rotor element is θ, and 90°≤θ≤150°, preferably 110°≤θ≤130°.

[0019] In the technical solution, the helix angle of the screw flight of the mixing rotor element is greater than or equal to 90° and less than or equal to 150°. If the helix angle is too small, the space formed between the screw flights will contain too little material, and the mixing rotor element will have too short a shearing mixing time for the material, which is not conducive to the full mixing of the material. If the helix angle is too large, the space formed between the screw flights will contain too much material, and as the material continuously advances, the material close to the screw element cannot be updated, which can easily cause high-solid-content material to deposit inside the mixing rotor element, and low-solid-content material to flow forward from the outer layer of the mixing rotor element, which can also easily cause uneven mixing of the material. The technical solution can effectively ensure the full and uniform mixing of the material.

[0020] According to some embodiments of the present application, the screw flight conveying element includes a first screw flight conveying element and a second screw flight conveying element, the outer diameter of the screw is D, the pitch of the first screw flight conveying element is L1, the pitch of the second screw flight conveying element is L2, 0.8D≤L1≤1.2D, and 0.5D≤L2≤0.8D.

[0021] In the technical solution, the screw includes a first screw flight conveying element and a second screw flight conveying element with different pitches, and the screw flight conveying elements with different pitches adjust the transmission speed of the material, so that the material can be transmitted at variable speeds, facilitating smooth transmission, full mixing and shearing of the material in the twin-screw machine, and finally making the material more compact under the pressure built by the screw.

[0022] In addition, the pitch affects the volume of the screw groove, thereby affecting the extrusion amount and shearing mixing degree of the material. If the pitch is too small, the extrusion amount is insufficient, which is not conducive to improving the production efficiency of the pole piece. If the pitch is too large, the volume of the screw groove is too large, and too much material is accumulated between the screw grooves, thereby causing the material in the screw groove to be unable to be updated in time, affecting the uniformity of the dispersion and mixing of the material. By setting the pitch of the second screw element to be between 0.5D and 0.8D and setting the pitch of the first screw flight conveying element to be between 0.8D and 1.2D, the extrusion amount of the screw and the uniformity of the mixing of the material can be effectively balanced.

[0023] According to some embodiments of the present application, 0.9D≤L1≤1.1D, and 0.6D≤L2≤0.7D.

[0024] In the technical solution, the pitch of the second screw element is set to be between 0.5D and 0.8D, and the pitch of the first screw flight conveying element is set to be between 0.8D and 1.2D, which can further improve the extrusion amount of the screw and the uniformity of the mixing of the material.

[0025] According to some embodiments of the present application, the screw comprises a plurality of groups of mixing rotor conveying assemblies, each group of the mixing rotor conveying assemblies comprising two mixing rotor elements and one second threaded conveying element arranged in sequence along the conveying direction of the screw, the second threaded conveying element being directly connected with the mixing rotor elements along the axis of the screw, the two mixing rotor elements being connected in mirror symmetry with each other.

[0026] In the above technical solution, the two mixing rotor elements are connected in mirror symmetry with each other along the axis of the screw to shear and knead the material. However, the transmission capacity of the mixing rotor element itself is weak. In order to prevent the material from depositing in the mixing rotor element and even causing the screw to seize, the mixing rotor conveying assembly of the technical solution directly connects a second threaded conveying element downstream of the mixing rotor element, so that the material after being sheared and kneaded by the mixing rotor element can be timely transmitted. Therefore, the structure of the overall mixing rotor conveying assembly ensures that the material is fully sheared and mixed while ensuring that the material can be smoothly transmitted.

[0027] According to some embodiments of the present application, the threaded conveying element further comprises a third threaded conveying element, the pitch of the third threaded conveying element being L3, 0.2D≤L3≤0.5D, preferably 0.3D≤L3≤0.45D.

[0028] In the above technical solution, the threaded conveying element comprises a third threaded conveying element, and the pitch of the third threaded conveying element is smaller than the pitches of the first threaded conveying element and the second threaded conveying element. The third threaded conveying element can further reduce the material transmission speed, further promote the pressure building of the material, make the material more compact, and better interface fusion, and facilitate uniform delivery of the compacted material out of the twin-screw machine, which is conducive to further ensuring the uniformity of the subsequent extruded film.

[0029] The pitch of the third threaded conveying element is set to be between 0.2D and 0.5D, which is conducive to ensuring the material conveying amount while achieving sufficient uniform conveying effect of the material, ensuring the compactness and uniformity of the material.

[0030] According to some embodiments of the present application, the screw comprises a plurality of groups of mixing rotor conveying assemblies, each group of the mixing rotor conveying assemblies comprising two mixing rotor elements and one second threaded conveying element arranged in sequence along the conveying direction of the screw, the second threaded conveying element being directly connected with the mixing rotor elements along the axis of the screw, the two mixing rotor elements being connected in mirror symmetry with each other.

[0031] In the technical solution, the first threaded conveying element with a long pitch is arranged upstream of the screw rod, which has high conveying efficiency and is beneficial to conveying the material to the downstream mixing rotor element; the mixing rotor conveying assembly and the first threaded conveying element are alternately arranged in the middle section of the screw rod, which ensures that the material is fully sheared and mixed and can be smoothly transmitted to the tail end of the screw rod; the first threaded conveying element, the second threaded conveying element and the third threaded conveying element with gradually decreasing pitches are sequentially arranged at the tail end of the screw rod, so as to effectively reduce the material transmission speed, fully build pressure on the material, make the material more compact and uniform, and finally the third threaded conveying element uniformly sends out the compacted material from the twin-screw machine, which is beneficial to further ensuring the uniformity of the subsequent extrusion and molding of the membrane.

[0032] According to some embodiments of the present application, the thread groove depth of the threaded conveying element is H, the outer diameter of the screw rod is D, and 0.1D≤H≤0.15D, preferably 0.12D≤H≤0.14D.

[0033] In the technical solution, the thread groove depth of the threaded conveying element is set to be between 0.1D and 0.15D. If the thread groove depth is too large, the structural strength of the screw rod will be affected, which will cause the screw rod to be easily sheared under a large torsion, so that the thread groove depth is too deep and the rotation speed and processing capacity of the screw rod are limited. If the thread groove depth is too small, the conveying capacity and extrusion capacity of the screw rod will be reduced, and the shearing force of the screw rod on the material will be too strong, which will increase the risk of damage to the binder fiber structure. The thread groove depth of the threaded conveying element in the technical solution can effectively balance the structural strength, processing capacity and conveying capacity of the screw rod, and effectively reduce the risk of damage to the binder structure caused by excessive shearing force, thereby effectively ensuring the manufacturing quality of the pole piece.

[0034] According to some embodiments of the present application, the twin-screw machine comprises a barrel and a screw rod, the screw rod is rotatably arranged in the barrel, and the gap between the outer circumferential surface of the screw rod and the inner wall of the barrel is L4, 0.1mm≤L4≤0.6mm, preferably 0.3mm≤L4≤0.5mm.

[0035] If the gap between the screw rod and the barrel is too large, the backflow and leakage of the material will be serious, which will cause the fluctuation of the extrusion pressure and affect the extrusion capacity of the screw rod. In addition, the increase of the backflow and leakage will cause the powder mixture and the solution to be insufficiently soaked and mixed, which will cause the material to be overheated due to the increased friction, and will cause irreversible damage to the binder and other materials. However, if the gap between the screw rod and the barrel is too small, the slight deformation of the screw rod during the extrusion process will cause the screw rod to rub against the inner wall of the barrel, which will on the one hand introduce metal debris and bring risks to the battery life and safety, and on the other hand, the mechanical friction will also affect the service life of the twin-screw machine and increase the equipment cost.

[0036] The gap between the screw and the barrel is limited to 0.1mm to 0.6mm, which can effectively reduce the backflow and leakage, improve the sufficiency of the powder mixture and the solution infiltration mixing, reduce the risk of damaging the material properties due to excessive heat generated by material friction, effectively ensure the stability of the material properties, and improve the production quality of the battery; at the same time, effectively reduce the risk of friction between the screw and the barrel, effectively ensure the service life of the double screw machine, and effectively avoid the mixing of metal debris into the material.

[0037] According to some embodiments of the present application, the first feeding mechanism is located upstream of the second feeding mechanism in the conveying direction of the screw.

[0038] In the above technical solution, the first feeding mechanism is arranged upstream of the second feeding mechanism, so that the powder mixture is gradually and uniformly mixed with the solution during the transmission of the screw after entering the mixing mechanism, effectively ensuring the sufficiency of the contact between the powder mixture and the solution, and further improving the uniformity of the material of the pole piece.

[0039] According to some embodiments of the present application, the first feeding mechanism is a loss-in-weight scale.

[0040] In the above technical solution, the first feeding mechanism is a loss-in-weight scale, which can realize high-precision continuous quantitative feeding through static weighing, effectively ensuring the reliability, accuracy and stability of the powder mixture feeding, and facilitating stable control of the ratio of the powder mixture and the solution, thereby ensuring the uniformity and consistency of the material mixing and effectively improving the production quality of the battery.

[0041] According to some embodiments of the present application, the second feeding mechanism is a metering pump.

[0042] In the above technical solution, the second feeding mechanism is a metering pump, which can deliver the solution at a stable flow rate, effectively ensuring the reliability, accuracy and stability of the solution feeding, and facilitating stable control of the ratio of the powder mixture and the solution, thereby ensuring the uniformity and consistency of the material mixing and effectively improving the production quality of the battery.

[0043] According to some embodiments of the present application, the extrusion die includes a die body and a flow uniformizing plate, the die body is provided with a feeding port, a discharging port and a material cavity communicating with the feeding port and the discharging port, the flow uniformizing plate is arranged in the material cavity, the flow uniformizing plate divides the material cavity into a first cavity communicating with the feeding port and a second cavity communicating with the discharging port, the flow uniformizing plate is provided with a plurality of through holes, and the plurality of through holes communicate the first cavity and the second cavity.

[0044] In the technical solution, the flow uniformizing plate is arranged in the extrusion die head, the flow uniformizing plate is designed to effectively adjust the extrusion speed of the extrusion die head along the length direction of the discharge port, so that the extrusion speed of the material along the length direction of the discharge port is more uniform, thereby improving the uniformity of the material extruded along the length direction of the discharge port.

[0045] According to some embodiments of the present application, along the length direction of the discharge port, the diameter of the through hole gradually increases from the middle of the flow uniformizing plate to both sides.

[0046] In the technical solution, the diameter of the through hole is limited to adjust the flow resistance of the material, so that the material can be distributed from the middle to both sides of the length direction of the discharge port, thereby improving the uniformity of the material extruded along the length direction of the discharge port.

[0047] According to some embodiments of the present application, the material cavity includes a flow distribution area, a buffer area and a pressure building area, which are arranged in sequence along the direction from the feed port to the discharge port, the cross-sectional area of the flow distribution area gradually increases from the feed port to the buffer area, and the cross-sectional area of the pressure building area gradually decreases from the buffer area to the discharge port.

[0048] In the technical solution, the material cavity is divided into a flow distribution area, a buffer area and a pressure building area, the flow distribution area distributes the material entering the material cavity through the feed port, so that the material can fully fill the material cavity, especially can spread along the length direction of the discharge port, and the pressure building area further compacts the material in the material cavity, thereby effectively ensuring the uniformity and continuity of the extruded film.

[0049] According to some embodiments of the present application, the flow uniformizing plate is arranged in the pressure building area and / or the buffer area.

[0050] In the technical solution, the flow uniformizing plate is arranged in the pressure building area and / or the buffer area, which is beneficial to further ensure the uniformity of the material extruded along the length direction of the discharge port.

[0051] In a second aspect, the present application provides a pole piece manufacturing equipment, comprising: the film preparation device according to any one of the above-mentioned solutions, which is used for extruding a film; and a composite device arranged downstream of the film preparation device, which is used for compositing a substrate and the film to form a pole piece.

[0052] In the technical solution, the pole piece manufacturing equipment includes a film preparation device and a composite device arranged downstream of the film preparation device, the film preparation device directly mixes and uniformly mixes a powder mixture and a solution used for forming an active material layer and extrudes the mixture and the solution into an active material film, and the composite device composites the active material film and a substrate to obtain a pole piece. The overall pole piece manufacturing equipment has high integration, and effectively improves the production quality and production efficiency of the pole piece.

[0053] Thirdly, this application provides a method for preparing a membrane, comprising: mixing a first binder with powder to form a powder mixture; dissolving a second binder in a solvent to form a solution; mixing the powder mixture and the solution to form an active substance mixture; and extruding the active substance mixture into a membrane. Attached Figure Description

[0054] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0055] Figure 1 This is a front view of the structure of a membrane fabrication apparatus provided in some embodiments of this application;

[0056] Figure 2 A front view of the screw structure of a twin-screw compressor provided in some embodiments of this application;

[0057] Figure 3 A front view of a mixing rotor element provided in some embodiments of this application;

[0058] Figure 4 for Figure 3 A side view of the internal mixing rotor element shown;

[0059] Figure 5 A front view of a first threaded conveying element provided for some embodiments of this application;

[0060] Figure 6 A front view of a second threaded conveying element provided for some embodiments of this application;

[0061] Figure 7 A front view of a third threaded conveying element provided for some embodiments of this application;

[0062] Figure 8 A simplified structural diagram of the first feeding mechanism provided for some embodiments of this application;

[0063] Figure 9 A simplified structural diagram of the second feeding mechanism provided in some embodiments of this application;

[0064] Figure 10 Front sectional view of an extrusion die provided in some embodiments of this application;

[0065] Figure 11 This is a schematic diagram of the structure of a flow equalization plate provided in some embodiments of this application;

[0066] Figure 12 A plan view of an extrusion die provided for some embodiments of the present application;

[0067] Figure 13 A schematic diagram of an overall structure of a pole piece manufacturing apparatus provided for some embodiments of the present application;

[0068] Figure 14 A schematic diagram of a simple structure of a pole piece manufacturing apparatus provided for some embodiments of the present application;

[0069] Figure 15 A schematic diagram of a structure of a cutting mechanism provided for some embodiments of the present application; Figure 13

[0070] Figure 16 A schematic diagram of a structure of a cutting mechanism provided for some embodiments of the present application;

[0071] Figure 17 A schematic diagram of a structure of a cutting mechanism provided for some embodiments of the present application;

[0072] Figure 18 A schematic diagram of a simple structure of a pole piece manufacturing apparatus provided for some embodiments of the present application;

[0073] Figure 19 A schematic diagram of a flow of a film sheet manufacturing method provided for some embodiments of the present application.

[0074] In the drawings, the drawings are not drawn according to the actual scale.

[0075] ​Label description: 1000 - pole piece manufacturing equipment; 100 - diaphragm preparation device; 10 - mixing mechanism; 11 - screw; 111 - first threaded conveying element; 112 - second threaded conveying element; 113 - third threaded conveying element; 114 - banbury rotor element; 1141 - screw rib; 12 - barrel; 20 - first feeding mechanism; 21 - hopper; 22 - stirring motor; 23 - stirring paddle; 24 - feeding motor; 25 - feeding screw; 26 - first weighing table; 30 - second feeding mechanism; 31 - storage hopper; 32 - measuring hopper; 33 - second weighing table; 34 - pump body; 40 - extrusion die; 41 - die body; 42 - feeding port; 43 - discharging port; 44 - material cavity; 441 - flow dividing area; 442 - buffer area; 443 - pressure building area; 45 - flow equalizing plate; 451 - through hole; 200 - compounding device; 210 - unwinding mechanism; 220 - rolling mechanism; 221 - first pressure roller; 230 - thinning mechanism; 231 - second pressure roller; 300 - edge trimming device; 310 - cutting mechanism; 311 - base; 312 - hob; 313 - first guide rail; 314 - first size measuring element; 320 - rejection mechanism; 321 - blade; 322 - second guide rail; 323 - second size measuring element; 400 - drying device; 500 - active material diaphragm; 600 - base material. DETAILED DESCRIPTION

[0076] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0077] Therefore, the detailed description of the embodiments of the present application provided below in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0078] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to make the technical solutions of the present application clearer, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0079] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0080] In the description of the embodiments of the present application, 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 technical features indicated. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0081] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0082] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two).

[0083] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0084] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "set", "mount", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected, signal connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0085] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length, width, and other dimensions of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0086] The electrode sheet mentioned in the present application is an important component of a battery cell, which includes an electrode assembly composed of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell mainly works by moving metal ions between the positive electrode sheet and the negative electrode sheet. The electrode sheet includes a current collector (i.e., a substrate as described below) and an active material layer. Specifically, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, and the positive electrode current collector without the positive electrode active material layer protrudes from the positive electrode current collector with the positive electrode active material layer, which can serve as a positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, and the negative electrode current collector without the negative electrode active material layer protrudes from the negative electrode current collector with the negative electrode active material layer, which can serve as a negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon, etc. In order to ensure that no fusing occurs when passing a large current, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together.

[0087] The film mentioned in the present application refers to a strip-shaped active material layer film formed after the active material mixture is extruded and shaped. The active material layer film can form an electrode sheet by being attached to a current collector.

[0088] In the present application, the battery cell suitable for the prepared electrode sheet can include a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., which is not limited in the embodiments of the present application.

[0089] The development of battery production technology needs to progress in many aspects, such as energy density, production efficiency, production quality, etc.

[0090] Traditional pole piece preparation adopts wet coating process, mainly to prepare slurry of binder, active material, conductive agent and other materials, then wet coating the slurry on the surface of the current collector, and then the current collector is put into a high temperature oven to evaporate the solvent to obtain the required pole piece. The process of preparing pole piece by wet coating has many shortcomings: (1) the slurry has low solid content, large amount of solvent is used, which has the disadvantages of large drying energy consumption and large equipment investment, and the solvent has the disadvantage of toxicity and environmental unfriendliness; (2) the pole piece also has the problem of uneven distribution of active material layer components in the drying process due to the floating of the binder, which seriously restricts the battery performance; (3) due to the problems of cracking and the like, it is difficult to meet the preparation requirements of the pole piece with thick active material layer, and the energy density of the battery has little room for improvement.

[0091] In order to avoid the defects of wet coating process for preparing pole piece, some existing battery technologies adopt dry process to prepare pole piece, the dry process mainly mixes the electrode active material, conductive agent and dry binder uniformly, without adding a large amount of solvent, and relies on the fiberization of the dry binder to form a network structure to bundle and fix the electrode active material and conductive agent in the binder fiber grid, to prepare a self-supporting structure pole piece film, and then the pole piece film is combined with the current collector to prepare a battery pole piece. Compared with the traditional wet coating method for preparing pole piece, this process can effectively reduce the drying energy consumption and cycle, reduce environmental pollution, and easily realize thick pole piece manufacturing and reduce the risk of pole piece cracking; at the same time, it can avoid the floating of the binder and improve the uniformity of the component distribution of the active material layer; in general, it can effectively improve the production efficiency and production quality of the pole piece, and is conducive to improving the energy density of the battery.

[0092] However, the inventors found that the active material layer film prepared by dry process still has the problems of poor structure uniformity and uneven component distribution, and has the defect of low energy density.

[0093] The inventors analyzed the reasons and found that: (1) the binder is easy to clump, which causes uneven dispersion, resulting in a relatively loose structure of the active material mixture and uneven distribution of each component; (2) because there is no solvent in the active material mixture, the particles are difficult to slip during compaction, resulting in poor plasticity and ductility of the active material mixture, making it difficult to achieve high-density compaction and affecting the improvement of its energy density; (3) because there is no solvent, the particles are difficult to slip, and the friction between the particles is large, so the active particles are easy to break the fiberized binder structure during the production of the active material film and the pole piece, thereby reducing the utilization efficiency of the binder, so it is necessary to add an excessive amount of fiberizable binder to the active material mixture during preparation to maximize the role of the binder. The excessive amount of binder reduces the proportion of active material, which also affects the improvement of the energy density.

[0094] Based on the above reasons, in order to solve the problems of poor structure uniformity and low energy density of the extruded film sheet, the present application provides a film sheet preparation device, which comprises a mixing mechanism, a first feeding mechanism, a second feeding mechanism and an extrusion die. The first feeding mechanism is used to add a powder mixture containing powder and a first binder to the mixing mechanism. The second feeding mechanism is used to add a solution containing a second binder to the mixing mechanism. The mixing mechanism is used to mix the powder mixture and the solution. The extrusion die is connected to the discharge end of the mixing mechanism and is used to extrude the film sheet.

[0095] When the film sheet preparation device is applied to the preparation of the active material layer film sheet of the pole piece, the first feeding mechanism can be used to add a powder mixture containing electrode active material powder and a first binder which can be fiberized and is not easy to dissolve in the solvent or has poor solubility in the solvent to the mixing mechanism. The second feeding mechanism can be used to add a solution containing a second binder to the mixing mechanism. The mixing mechanism can mix the powder mixture and the solution. The first type of binder can be fiberized to form a mesh structure and fix the raw materials such as electrode active materials in the binder fiber grid to form a rib mesh structure active material mixture. The solution containing the second type of binder can effectively increase the flexibility and adhesion of the active material mixture, so as to form a lump-like active material mixture with certain viscosity and plasticity. The extrusion die can be used to extrude the active material mixture into an active material film sheet.

[0096] In the first aspect, the present application can mix the first binder which can be fiberized and is not easy to dissolve in the solvent or aqueous solution in advance to form a powder mixture, which can avoid the problem of clumping and poor dispersion of the first binder after being directly mixed in the solution due to its poor solubility, thereby improving the dispersion uniformity of the first binder in the active material mixture. In the second aspect, the present application can dissolve the second binder which plays a role of adhesion in the solvent to form a solution, and then mix the solution with the powder mixture, which can effectively ensure the dispersion uniformity of the second binder in the active material mixture and fully play the role of the second binder in the flexibility and adhesion of the active material mixture. In the third aspect, compared with the pure dry film sheet preparation process, the present application can add the solution to the mixture through the second feeding mechanism, thereby effectively improving the structure looseness of the active material mixture, improving the plasticity and ductility of the active material mixture, improving the compactibility of the film sheet, and further improving the volume ratio of the active material of the pole piece. Moreover, the addition of the solution can effectively reduce the demand for the first binder, thereby being beneficial to improving the content ratio of the active material and effectively improving the energy density of the battery by improving the ratio of the active material. In general, the film sheet preparation device of the present application can effectively improve the mixing uniformity and the uniformity of the distribution of each component of the active material mixture, and is beneficial to improving the ratio of the active material, thereby effectively improving the production quality of the pole piece and the energy density of the battery.

[0097] The film preparation device 100 disclosed by the embodiments of the present application can be used in the electrode plate manufacturing equipment, but also can be used in the preparation process of various plastic film preparation or other fields of extruded strip material. In order to facilitate the description, the film preparation device is used to prepare the active material film as an example.

[0098] Please refer to Figure 1 , Figure 1 The film preparation device provided by some embodiments of the present application is shown in the structure front view. The film preparation device 100 provided by some embodiments of the present application includes a mixing mechanism 10, a first feeding mechanism 20, a second feeding mechanism 30 and an extrusion die 40. The first feeding mechanism 20 is used to add the powder mixture containing the powder and the first binder into the mixing mechanism 10. The second feeding mechanism 30 is used to add the solution containing the second binder into the mixing mechanism 10. The mixing mechanism 10 is used to mix the powder mixture and the solution. The extrusion die 40 is connected to the discharge end of the mixing mechanism 10 and is used to extrude the film.

[0099] The mixing mechanism 10 is used to realize the mixing of the powder mixture and the solution. The implementation structure of the mixing mechanism 10 has many kinds. For example, the mixing mechanism 10 can be a kneader, an internal mixer or the like. It can be understood that when the mixing mechanism 10 adopts the mixing device such as the kneader or the internal mixer, the film preparation device 100 should also include an extrusion unit. The extrusion unit provides the extrusion power for the extrusion of the powder mixture from the extrusion die 40. The extrusion unit can be a separate structure arranged between the mixing mechanism 10 and the extrusion die 40. For example, the extrusion unit can include a cavity and an extrusion power source. The cavity is connected to the mixing mechanism 10 and the extrusion die 40. The active material mixture mixed by the mixing mechanism 10 enters the cavity. The extrusion power source applies extrusion pressure to the active material mixture, so that the active material mixture is shaped and extruded through the extrusion die 40. The extrusion power source can be a conventional power providing mechanism such as a hydraulic telescopic structure.

[0100] Of course, in some embodiments, the mixing mechanism 10 can integrate the mixing and the conveying and extrusion, that is, the active material mixture is fully mixed at the same time as the extrusion power is provided to the active material mixture.

[0101] The first feeding mechanism 20 can have various embodiments. The first feeding mechanism 20 can include a conventional powder mixing mechanism 10, such as a double planetary mixer, a horizontal double-shaft spiral ribbon mixer, a double helical cone mixer, an inclined intensive mixer, etc., to sufficiently mix the first binder and the powder (in this embodiment, the powder is an electrode active material powder) and then feed the mixed powder into the mixing mechanism 10. Of course, the first feeding mechanism 20 can also include a weighing structure to control the amount of the powder mixture fed into the mixing mechanism 10. The embodiment of the present application does not limit the structure of the first feeding mechanism 20 and any structure capable of feeding the powder mixture can be used.

[0102] Similarly, the second feeding mechanism 30 can also have various embodiments as long as it is capable of feeding the solution.

[0103] The powder in the embodiment of the present application refers to a powder used to prepare an active material layer. The powder can include an electrode active material, a conductive agent, etc. For example, when the electrode tab is a lithium battery electrode tab, the positive electrode active material can include one or more of a lithium-containing phosphate having an olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials and other conventional materials that can be used as a positive electrode active material of a battery can also be used.

[0104] The negative electrode active material can include one or more of a carbon material, a silicon material, lithium, a lithium alloy material, etc. The carbon material can include natural graphite, artificial graphite, mesocarbon microbeads, hard carbon, soft carbon, etc. The silicon material can include silicon monoxide, silicon nanowires, a composite silicon-carbon material, etc. The lithium and lithium alloy material can include at least one of titanium oxide, lithium, a lithium alloy, and a material capable of forming a lithium alloy.

[0105] The conductive agent can include one or more of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0106] In the embodiment, the first binder can be a fibrillatable binder that is not easily dissolved in the solution to increase the structural strength of the active material mixture and allow the active material mixture to form a mesh structure. The embodiment of the present application does not limit the type of the first binder and, for example, the first binder can be a fibrillatable fluorine-containing high molecular material such as polytetrafluoroethylene.

[0107] In the embodiment, the second binder is mainly used to increase the flexibility and adhesion of the active material mixture. The embodiment of the present application does not limit the type of the second binder and, for example, the second binder can be polyvinylidene fluoride.

[0108] The solvent forming the solution can include a small molecule alcohol or ester. For example, the solvent can be N-methyl pyrrolidone.

[0109] The extrusion die 40 is used to shape the extrusion shape of the active material mixture, so that the active material mixture is extruded into a three-dimensional structure of a strip-shaped film structure. The powder mixture and the solution are mixed in the mixing mechanism 10 to form the active material mixture, and the active material mixture is extruded through the extrusion die 40 to form the active material film 500.

[0110] The structure type of the extrusion die 40 is not particularly limited in this embodiment, and the extrusion die 40 can adopt a conventional plunger structure, a clothes hanger structure, or a fish tail structure, as long as the active material mixture is uniformly extruded to meet the size requirements of the film.

[0111] The film preparation device 100 provided by the technical scheme of the present application can realize the purpose of directly mixing the powder mixture and the solvent and then extruding the powder mixture into a film. At the same time, the first feeding mechanism 20 and the second feeding mechanism 30 are provided to facilitate classified feeding into the mixing mechanism 10. When the film preparation device 100 is applied to the preparation of the active material layer film of the pole piece, the first feeding mechanism 20 can be used to add a powder mixture containing electrode active material powder and a first binder that is not soluble in the solvent or has poor solubility in the solvent to the mixing mechanism 10, and the second feeding mechanism 30 can be used to add a solution containing a second binder to the mixing mechanism 10. The mixing mechanism 10 mixes the powder mixture and the solution, the first type of binder is fiberized to form a reticular structure and fixes the electrode active material and other raw materials in the binder fiber grid to form an active material mixture with a muscle grid structure, the solution containing the second type of binder effectively increases the flexibility and adhesion of the active material mixture, thereby forming a lump-shaped active material mixture with certain viscosity and plasticity, and the active material mixture is extruded into an active material film 500 through the extrusion die 40. On the one hand, the technical scheme of the present application can avoid the problem of clumping and poor dispersion of the first binder that can be fiberized when the first binder is directly mixed into the solution due to its poor solubility in the solvent, thereby improving the dispersion uniformity of the first binder in the active material mixture. On the other hand, the technical scheme of the present application can effectively ensure the sufficient solubility of the second binder that has a binding effect, thereby ensuring the dispersion uniformity of the second binder in the active material mixture. Thirdly, compared with a pure dry film preparation process, the technical scheme of the present application adds the solution through the second feeding mechanism 30, effectively improves the structural looseness of the active material mixture, and improves the plasticity and ductility of the active material mixture. Overall, the film preparation device 100 of the present application can effectively improve the mixing uniformity and the uniformity of the distribution of each component of the active material mixture, thereby improving the structural uniformity and the uniformity of the distribution of each component of the film, and further effectively improving the production quality of the pole piece.

[0112] According to some embodiments of the present application, as Figure 1As shown, the extrusion die 40 is directly connected to the discharge end of the mixing mechanism 10.

[0113] The extrusion die 40 is directly connected to the discharge end of the mixing mechanism 10. The mixing mechanism 10 then completes the mixing of the active substance mixture and provides extrusion power for the extrusion of the active substance mixture. In this embodiment, the mixing mechanism 10 can be a single-screw extruder, a twin-screw extruder, or other similar mechanisms.

[0114] The extrusion die 40 is directly installed at the discharge end of the mixing mechanism 10, and the overall film preparation device 100 integrates mixing and extrusion molding into one unit, with strong structural integration. Compared with structures where material mixing and extrusion molding are separate, the technical solution of this application effectively reduces material transfer time and repeated material shearing and conveying time, simplifies the production process, and improves the production efficiency of battery electrodes; at the same time, it effectively reduces the demand for production equipment, saves manufacturing costs, and has strong practicality and outstanding economic benefits.

[0115] Please refer further to some embodiments of this application. Figure 2 , Figure 2 This is a front view of the screw structure of a twin-screw machine provided in some embodiments of this application. The mixing mechanism 10 is a twin-screw machine.

[0116] A twin-screw extruder, also known as a twin-screw press, mainly consists of an extrusion system and a drive system. The extrusion system comprises two parallel screws 11 and a barrel 12. Material is sheared and moved within the barrel 12 by the co-rotation or counter-rotation of the two screws 11. The drive system primarily drives the two screws 11 to rotate, supplying them with the torque required during the extrusion process. The drive system typically consists of a motor, reducer, and bearings. The screws 11 of a twin-screw press can have a modular structure, including one or more components such as threaded conveying elements, mixing rotor elements, kneading elements, and toothed discs, to achieve the functions of conveying, dispersing, shearing, kneading, and pressurizing the active material mixture. The threaded conveying elements primarily function to convey and pressurize the active material mixture within the twin-screw press, while the mixing rotor elements, kneading elements, and toothed discs primarily function to shear and knead the active material mixture within the twin-screw press. The screw 11 of a twin-screw compressor is composed of conventional components such as threaded conveying elements, mixing rotor elements, kneading elements, and toothed discs. The basic structure of these components will not be described in detail in this embodiment.

[0117] The twin-screw extruder in this embodiment can be a conventional commercially available twin-screw extruder. This embodiment will not elaborate on the detailed structural components of the twin-screw extruder. Nor is the structure of the screw 11 limited to a single feature; it only needs to meet the requirements for preparing materials with a certain strength and flexibility.

[0118] The mixing mechanism 10 is a double screw machine. The double screw machine fully mixes, shears and kneads the powder mixture and the solution, realizes the uniform mixing of the powder mixture and the solution in the double screw machine, and ensures the full mixing and infiltration between the powder and the solution. Meanwhile, the double screw machine realizes the fiberization of the first binder, so that the active material mixture can form a group of structures with certain viscosity, plasticity and ductility, thereby further ensuring the uniformity of the structure of the active material mixture and the uniformity of the distribution of each component. In addition, the double screw machine can play a role in conveying and building pressure for the active material mixture during the mixing process, and provide extrusion power for the extrusion molding of the diaphragm, so that the mixed mixture can be extruded into a diaphragm through the extrusion die 40.

[0119] According to some embodiments of the present application, the screw 11 of the double screw machine is composed of alternatingly arranged banbury rotor elements 114 and threaded conveying elements.

[0120] As described above, the screw 11 of the double screw machine can be in a building block structure, and the screw 11 of the double screw machine can include one or more of threaded conveying elements, banbury rotor elements 114, kneading elements, toothed discs and the like, and the selection, number and arrangement sequence of different elements play a crucial role in the mixing and shearing effect of different materials.

[0121] The screw 11 of the present embodiment is composed of alternatingly arranged banbury rotor elements 114 and threaded conveying elements. The threaded conveying elements convey the active material mixture, and the banbury rotor elements 114 fully disperse, shear and knead the active material mixture to fully balance the shearing and mixing and conveying capacity of the diaphragm preparation device 100.

[0122] The inventors of the present application have found that the shearing force of the banbury rotor element 114 is relatively mild, which can ensure the fiberization of the first binder without damaging the fiber structure, thereby effectively reducing the risk of over-shearing leading to the failure of the first binder, and further effectively ensuring the structural toughness of the active material mixture. At the same time, it can effectively reduce the risk of over-shearing leading to the breakage of the active electrode particle morphology, thereby reducing the risk of battery gas generation and the risk of low initial efficiency of the battery, and effectively ensuring the energy density.

[0123] According to some embodiments of the present application, please continue to refer to Figure 2 , and further refer to Figure 3 , Figure 3 The front view of the banbury rotor element provided for some embodiments of the present application is shown in FIG. 10. The width of the screw rib 1141 of the banbury rotor element 114 is d, and the outer diameter of the screw 11 is D. 0.02D≤d≤0.15D, and preferably 0.04D≤d≤0.1D.

[0124] The structure of the banbury rotor element is shown in FIG. 11.Figure 3 As shown, the use process of the mixing rotor element 114 is generally a pair of mixing rotor elements 114 used in cooperation, along the axis of the screw rod 11 (the X direction as shown in the figure), and the pair of mixing rotor elements 114 are connected in mirror symmetry with each other. The screw flights 1141 of the mixing rotor element 114 enclose a containing space, which is used to contain a certain active material mixture. The active material mixture is mainly subjected to shearing kneading in the containing space and the slit between the screw flights 1141 and the inner wall of the barrel 12, which plays a role in uniform mixing of the active material mixture and shearing of the binder. Figure 2 And Figure 3 As shown in the figure, the screw flights 1141 of the mixing rotor element 114 enclose a containing space, which is used to contain a certain active material mixture. The active material mixture is mainly subjected to shearing kneading in the containing space and the slit between the screw flights 1141 and the inner wall of the barrel 12, which plays a role in uniform mixing of the active material mixture and shearing of the binder.

[0125] In this embodiment, the width d of the screw flights 1141 of the mixing rotor element 114 and the outer diameter D of the screw rod 11 can be constant values, and the width d of the screw flights 1141 of the mixing rotor element 114 can be any value greater than or equal to 0.02D and less than or equal to 0.15D, such as 0.02D, 0.03D, 0.035D, 0.05D, 0.1D, 0.12D, 0.15D, etc.

[0126] Preferably, the width d of the screw flights 1141 of the mixing rotor element 114 can be any value greater than or equal to 0.04D and less than or equal to 0.1D, such as 0.04D, 0.05D, 0.06D, 0.075D, 0.08D, 0.09D, 0.1D, etc.

[0127] For example, the width d of the screw flights 1141 of the mixing rotor element 114 is 0.06D.

[0128] The inventors have found that if the width of the screw flights 1141 of the mixing rotor element 114 is too wide, the free volume of the containing space is small, and the resistance of the channel formed by the space between the screw flights 1141 and the inner wall of the barrel 12 increases, which reduces the rate of movement of the active material mixture subjected to shearing, and the number of times of shearing of the active material mixture is also reduced, which easily causes insufficient mixing of the active material mixture. On the contrary, if the width of the screw flights 1141 of the mixing rotor element 114 is too small, the free volume of the containing space increases, which easily causes the active material mixture to accumulate in the containing space. At the same time, the shearing rate of the active material mixture passing through the space between the screw flights 1141 and the barrel wall increases, and the number of times of shearing also increases, which easily causes problems such as excessive shearing of the active material mixture and damage to the structure of the binder. In the technical solution of the present application, the ratio of the width of the screw flights 1141 of the mixing rotor element 114 to the outer diameter of the screw rod 11 is set to be between 0.02 and 0.15, which can effectively ensure that the active material mixture is sufficiently and uniformly mixed while avoiding excessive shearing, thereby effectively ensuring the production quality of the diaphragm and further effectively ensuring the production quality of the battery.

[0129] According to some embodiments of the present application, please refer to Figure 3 and further refer to Figure 4 , Figure 4 Figure 8 is a side view of the screw rotor element shown in Figure 7, the helix angle of the screw flight 1141 of the screw rotor element 114 is θ, 90°≤θ≤150°, preferably, 110°≤θ≤130°. Figure 3

[0130] The helix angle of the screw flight 1141 refers to the angle between the starting end and the terminal end of the screw flight 1141 of the screw rotor element 114 in the plane perpendicular to the axis of the screw 11.

[0131] The helix angle θ of the screw flight 1141 can be any value greater than or equal to 90° and less than or equal to 150°, for example, θ can be 90°, 92°, 95°, 100°, 140°, 150°, etc.

[0132] Preferably, the helix angle θ of the screw flight 1141 can be any value greater than or equal to 110° and less than or equal to 130°, for example, θ can be 110°, 115°, 120°, 125°, 128°, 130°, etc.

[0133] For example, θ can be 120°.

[0134] The inventors found that if the helix angle is less than 90°, the space formed between the screw flights 1141 will contain too little active substance mixture, and the shear mixing time of the screw rotor element 114 on the active substance mixture will be too short, which is not conducive to the full mixing of the active substance mixture; if the helix angle is greater than 150°, the space formed between the screw flights 1141 will contain too much active substance mixture, as the active substance mixture continuously advances forward, the active substance mixture close to the screw element cannot be updated, which is easy to cause the deposition of high solid content material inside the screw rotor element 114, and the flow of low solid content material from the outer layer of the screw rotor element 114 forward, which is also easy to cause the uneven composition of the active substance mixture. The helix angle of the screw flight 1141 is designed to be greater than or equal to 90° and less than or equal to 150° in the technical solution of the present application, which can effectively ensure the full and uniform mixing of the active substance mixture.

[0135] According to some embodiments of the present application, please refer to Figure 2 and further refer to Figure 5 and Figure 6 , Figure 5 Figure 8 is a side view of the screw rotor element shown in Figure 7, the helix angle of the screw flight 1141 of the screw rotor element 114 is θ, 90°≤θ≤150°, preferably, 110°≤θ≤130°. Figure 6 ​A front view of a second threaded conveying element is provided for some embodiments of the present application. The threaded conveying element includes a first threaded conveying element 111 and a second threaded conveying element 112, the outer diameter of the screw rod 11 is D, the pitch of the first threaded conveying element 111 is L1, and the pitch of the second threaded conveying element 112 is L2, 0.8D≤L1≤1.2D, and 0.5D≤L2≤0.8D.

[0136] By setting the first threaded conveying element 111 and the second threaded conveying element 112 with different pitches, it is convenient to control the thread groove volume of the first threaded conveying element 111 and the second threaded conveying element 112. If the thread groove volumes of the first threaded conveying element 111 and the second threaded conveying element 112 are different, the processing amount of the active material mixture by the first threaded conveying element 111 and the second threaded conveying element 112 is different, which is convenient to provide different conveying force and extrusion force for the active material mixture to meet the different requirements of the screw rod 11 for conveying, building pressure, etc. of the active material mixture.

[0137] The outer diameter D of the screw rod 11 is a fixed value, and the pitch L1 of the first threaded conveying element 111 can be any value greater than or equal to 0.8D and less than or equal to 1.2D, for example, L1 can be 0.8D, 0.85D, 0.9D, 0.91D, 1.0D, 1.1D, 1.2D, etc. For example, L1 can be 1.2D.

[0138] The pitch L2 of the second threaded conveying element 112 can be any value greater than or equal to 0.5D and less than or equal to 0.8D, for example, L2 can be 0.5D, 0.6D, 0.65D, 0.7D, 0.8D, etc. For example, L2 can be 0.8D.

[0139] The first threaded conveying element 111 and the second threaded conveying element 112 with different pitches play a role in adjusting the transmission speed of the active material mixture, so that the active material mixture can be transmitted at variable speed, which is convenient for the smooth transmission, sufficient mixing and shearing of the active material mixture in the double screw machine, and finally more compact under the pressure building effect of the screw rod 11.

[0140] In addition, the pitch of the screw rod 11 affects the volume of the thread groove of the screw rod 11, thereby affecting the extrusion amount and shearing mixing degree of the active material mixture. If the pitch is too small, the extrusion amount is insufficient, which is not conducive to improving the production efficiency of the pole piece. If the pitch is too large, it is easy to cause the thread groove volume to be too large, and too much active material mixture to accumulate between the thread grooves, thereby causing the active material mixture in the thread groove to be unable to be updated in time, affecting the uniformity of the dispersion and mixing of the active material mixture. In the present application, the pitch of the second threaded element is set to be between 0.5D and 0.8D, and the pitch of the first threaded conveying element 111 is set to be between 0.8D and 1.2D, which can effectively balance the extrusion amount of the screw rod 11 and the uniformity of the mixing of the active material mixture.

[0141] According to some embodiments of the present application, 0.9D≤L1≤1.1D, 0.6D≤L2≤0.7D.

[0142] The outer diameter D of the screw 11 is a fixed value, the pitch L1 of the first threaded conveying element 111 can be any value greater than or equal to 0.9D and less than or equal to 1.1D, for example, L1 can be 0.9D, 0.91D, 0.92D, 0.93D, 0.96D, 0.98D, 1.05D, 1.1D, etc. Exemplarily, L1 can be 1.0D.

[0143] The pitch L2 of the second threaded conveying element 112 can be any value greater than or equal to 0.6D and less than or equal to 0.7D, for example, L2 can be 0.6D, 0.61D, 0.62D, 0.66D, 0.7D, etc. Exemplarily, L2 can be 0.6D.

[0144] By setting the pitch of the second threaded element to be between 0.5D and 0.8D and setting the pitch of the first threaded conveying element 111 to be between 0.8D and 1.2D, the mixing uniformity of the active substance mixture can be further improved while increasing the extrusion amount of the screw 11.

[0145] According to some embodiments of the present application, referring again to Figure 2 , the screw 11 includes a plurality of groups of banbury rotor conveying assemblies, each group of banbury rotor conveying assemblies includes two banbury rotor elements 114 and one second threaded conveying element 112 arranged in sequence along the conveying direction of the screw 11, the second threaded conveying element 112 is directly connected with the banbury rotor elements 114, and the two banbury rotor elements 114 are connected in mirror symmetry along the axis of the screw 11.

[0146] As mentioned above, the banbury rotor element 114 is usually used in pairs, and the pair of banbury rotor elements 114 are connected in mirror symmetry along the axis of the screw 11. The banbury rotor conveying assembly includes two banbury rotor elements 114, which are connected in mirror symmetry along the axis of the screw 11 and are connected with each other, and the screw flights 1141 of the two banbury rotor elements 114 form an accommodation space therebetween, which is used to accommodate a certain amount of active substance mixture. The active substance mixture is mainly subjected to shearing and kneading in the accommodation space and the gap between the screw flights 1141 and the inner wall of the barrel 12.

[0147] The second threaded conveying element 112 is directly connected with one of the banbury rotor elements 114, and the two banbury rotor elements 114 and the second threaded conveying element 112 are arranged in sequence along the conveying direction of the screw 11, that is, the second threaded conveying element 112 is arranged downstream of the two banbury rotor elements 114.

[0148] The mixing rotor element itself has weak transmission capacity. The technical scheme of the present application directly connects a second threaded conveying element 112 downstream of the mixing rotor element 114, so that the active substance mixture after being sheared and kneaded by the mixing rotor element 114 can be timely transmitted, which can effectively reduce the risk of deposition of the active substance mixture in the mixing rotor element 114, causing the screw rod 11 to be locked.

[0149] According to some embodiments of the present application, please refer again to Figure 2 , and further refer to Figure 7 , Figure 7 The third threaded conveying element provided by some embodiments of the present application is a front view. The threaded conveying element further includes a third threaded conveying element 113, and the pitch of the third threaded conveying element 113 is L3, 0.2D≤L3≤0.5D, preferably, 0.3D≤L3≤0.45D.

[0150] The pitch L3 of the third threaded conveying element is less than or equal to the pitch of the second threaded conveying element 112 and less than the pitch of the first threaded conveying element 111. Under the condition that the thread groove depths of the first threaded conveying element 111, the second threaded conveying element 112 and the third threaded conveying element 113 are the same, the active substance mixture processing amount of the third threaded conveying element 113 is relatively the smallest, and the active substance mixture transmission speed is relatively the lowest.

[0151] The outer diameter D of the screw rod 11 is a fixed value, and the pitch L3 of the third threaded conveying element 113 can be any value greater than or equal to 0.2D and less than or equal to 0.5D, such as 0.2D, 0.3D, 0.35D, 0.4D, 0.5D, etc.

[0152] Preferably, the pitch L3 of the third threaded conveying element 113 can be any value greater than or equal to 0.3D and less than or equal to 0.45D, such as 0.3D, 0.32D, 0.34D, 0.41D, 0.43D, 0.45D, etc.

[0153] For example, the pitch L3 of the third threaded conveying element 113 can be 0.4D.

[0154] The third threaded conveying element 113 can further reduce the transmission speed of the active substance mixture, further promote the pressure building of the active substance mixture, make the active substance mixture more compact, the interface fusion better, and facilitate the uniform delivery of the compacted active substance mixture to the twin-screw machine, which is beneficial to further ensure the uniformity of the subsequent extruded film.

[0155] The pitch of the third threaded conveying element 113 is set between 0.2D and 0.5D, which is beneficial to ensure the conveying amount of the active material mixture while achieving sufficient pressure build-up effect on the active material mixture, thus ensuring the compactness and uniformity of the active material mixture.

[0156] Please refer again to some embodiments of this application. Figure 2 The screw 11 includes a first threaded conveying element 111, a mixing rotor conveying assembly, a first threaded conveying element 111, a mixing rotor conveying assembly, a first threaded conveying element 111, a second threaded conveying element 112, and a third threaded conveying element 113 arranged sequentially along the conveying direction of the screw 11.

[0157] Among them, the conveying direction of screw 11 is along Figure 2 Extending in the X direction as shown, one or more first threaded conveying elements 111 can be provided, one or more mixing rotor conveying assemblies can be provided, one or more second threaded conveying elements 112 can be provided, and one or more third threaded conveying elements 113 can be provided.

[0158] like Figure 2 As shown, in some embodiments, the screw 11 includes six first threaded conveying elements 111, three sets of internal mixing rotor conveying assemblies, three first threaded conveying elements 111, two sets of internal mixing rotor conveying assemblies, four first threaded conveying elements 111, one second threaded conveying element 112, and four third threaded conveying elements 113 arranged sequentially along the conveying direction of the screw 11.

[0159] In other embodiments, the screw 11 may also have other structures. For example, the screw 11 may include a first threaded conveying element 111, a mixing rotor conveying assembly, a first threaded conveying element 111, a second threaded conveying element 112, and a third threaded conveying element 113 arranged sequentially along the conveying direction of the screw 11.

[0160] For example, the screw 11 may include six first threaded conveying elements 111, eight sets of mixing rotor conveying assemblies, four first threaded conveying elements 111, one second threaded conveying element 112, and four third threaded conveying elements 113 arranged sequentially along the conveying direction of the screw 11.

[0161] The upstream of the screw rod 11 is provided with the first threaded conveying element 111 with long pitch, which has high conveying efficiency and is beneficial to conveying the active substance mixture to the downstream banbury rotor element 114; the intermediate section of the screw rod 11 is alternately provided with the banbury rotor conveying assembly and the first threaded conveying element 111 to form the mixing section of the screw rod 11, which can ensure that the active substance mixture is sufficiently sheared and mixed and can be smoothly transmitted to the tail end of the screw rod 11; the tail end of the screw rod 11 is provided with the first threaded conveying element 111, the second threaded conveying element 112 and the third threaded conveying element 113 with gradually decreasing pitches, so as to effectively reduce the transmission speed of the active substance mixture, sufficiently build pressure on the active substance mixture, make the active substance mixture more compact and uniform, and finally the third threaded conveying element 113 uniformly sends out the compacted active substance mixture from the twin-screw machine, which is beneficial to further ensuring the uniformity of the subsequent extruded film.

[0162] According to some embodiments of the present application, please refer to Figures 5 to 7 , the thread groove depth of the threaded conveying element is H, the outer diameter of the screw rod 11 is D, and 0.1D≤H≤0.15D, preferably 0.12D≤H≤0.14D.

[0163] In the embodiment form of “the screw rod 11 comprises the first threaded conveying element 111, the second threaded conveying element 112 and the third threaded conveying element 113”, the thread groove depth of the first threaded conveying element 111, the second threaded conveying element 112 and the third threaded conveying element 113 is H.

[0164] The outer diameter D of the screw rod 11 can be a fixed value, and the thread groove depth H of the threaded conveying element can be any value greater than or equal to 0.1D and less than or equal to 0.15D, such as 0.1D, 0.11D, 0.12D, 0.135D, 0.14D, 0.15D, etc.

[0165] Preferably, the thread groove depth H of the threaded conveying element can be any value greater than or equal to 0.12D and less than or equal to 0.14D, such as 0.12D, 0.125D, 0.128D, 0.13D, 0.136D, 0.138D, etc.

[0166] For example, the thread groove depth H of the threaded conveying element can be 0.13D.

[0167] If the thread groove depth of the screw rod 11 is too large, the structural strength of the screw rod 11 will be affected, and the screw rod 11 is prone to shear failure under a large torsion, so that the thread groove depth is too deep, which can limit the rotation speed and processing capacity of the screw rod 11, and also cause too much active material mixture to accumulate between the thread grooves, thereby affecting the timeliness and uniformity of the active material mixture update in the thread groove. If the thread groove depth is too small, the conveying capacity and extrusion capacity of the screw rod 11 will be reduced, and the shear force of the screw rod 11 on the active material mixture will be too strong, which will increase the risk of damage to the binder fiber structure. The thread groove depth of the thread conveying element in the embodiment is set to be between 0.1D and 0.15D, which can effectively balance the structural strength, processing capacity and conveying capacity of the screw rod 11, and effectively reduce the risk of damage to the binder fiber structure caused by excessive shear force, thereby effectively ensuring the manufacturing quality of the pole piece.

[0168] According to some embodiments of the present application, please refer again to Figure 2 The double-screw machine includes a barrel 12 and a screw rod 11, the screw rod 11 is rotatably arranged in the barrel 12, and the gap between the outer periphery of the screw rod 11 and the inner wall of the barrel 12 is L4, 0.1mm≤L4≤0.6mm, preferably, 0.3mm≤L4≤0.5mm.

[0169] The barrel 12 provides a containing space for the active material mixture, and the outer periphery of the screw rod 11 refers to the outer periphery corresponding to the outer diameter of the screw rod 11. Based on the embodiment form that "the screw rod 11 includes a first thread conveying element 111, a second thread conveying element 112, a third thread conveying element 113 and a banbury rotor element 114", the gap between different sections of the screw rod 11 and the barrel 12 can be the same or different.

[0170] The gap L4 between the outer periphery of the screw rod 11 and the inner wall of the barrel 12 can be any value greater than or equal to 0.1mm and less than or equal to 0.6mm, for example, L4 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.45mm, 0.6mm, etc.

[0171] Preferably, L4 can be any value greater than or equal to 0.3mm and less than or equal to 0.5mm, for example, L4 can be 0.3mm, 0.32mm, 0.35mm, 0.4mm, 0.42mm, 0.46mm, 0.5mm, etc.

[0172] For example, L4 can be 0.5mm.

[0173] If the gap between the screw 11 and the barrel 12 is too large, the backflow and leakage of the active material mixture are serious, which easily causes the fluctuation of the extrusion pressure, thereby affecting the extrusion amount of the screw 11; and the increase of the backflow and leakage easily leads to the insufficient infiltration and mixing of the powder mixture and the solution, thereby causing the active material mixture to be overheated due to the intensified friction of the active material mixture, and causing irreversible damage to the binder and other materials; but if the gap between the screw 11 and the barrel 12 is too small, the slight deformation of the screw 11 during the extrusion of the active material mixture can cause the friction between the screw 11 and the inner wall of the barrel 12, which not only affects the service life of the double-screw machine, but also easily introduces metal debris, thereby bringing great hidden troubles to the battery life and safety. The gap between the screw 11 and the barrel 12 is limited to 0.1mm to 0.6mm in the technical scheme of the present application, which can effectively reduce the backflow and leakage, thereby improving the sufficiency of the infiltration and mixing of the powder mixture and the solution, further reducing the risk of damaging the properties of the active material mixture due to excessive heat generated by the friction of the active material mixture, effectively ensuring the stability of the properties of the active material mixture, thereby improving the production quality of the battery; at the same time, the risk of friction between the screw 11 and the barrel 12 is effectively reduced, thereby effectively ensuring the service life of the double-screw machine.

[0174] According to some embodiments of the present application, as shown in Figure 2 the first feeding mechanism 20 is located upstream of the second feeding mechanism 30 along the conveying direction of the screw 11.

[0175] The conveying direction of the screw 11 extends along the X direction as shown in Figure 2 As described above, the first feeding mechanism 20 is used to add the powder mixture containing the powder and the first binder to the mixing mechanism 10, and the second feeding mechanism 30 is used to add the solution containing the second binder to the mixing mechanism 10, and the first feeding mechanism 20 is arranged upstream of the second feeding mechanism 30, so that the powder mixture is first added to the mixing mechanism 10, and then the solution is added to the powder mixture being conveyed and stirred by the screw 11 through the second feeding mechanism 30, so that the powder mixture is gradually and uniformly infiltrated and mixed with the solution during the transmission of the screw 11, thereby effectively ensuring the sufficiency of the contact between the powder mixture and the solution, and further improving the uniformity of the mixing of the powder mixture and the solution.

[0176] According to some embodiments of the present application, the first feeding mechanism 20 is a loss-in-weight scale.

[0177] The loss-in-weight scale is an automatic weighing device that realizes high-precision continuous quantitative feeding by static weighing, which can reliably, accurately and stably feed the dry and scattered active material mixture such as powder, granules and tablets, thereby reducing the waste of the active material mixture and improving the consistency of the mixture.

[0178] The loss-in-weight scale is a commonly used feeding mechanism in the industry. The detailed structure of the loss-in-weight scale is not limited or described herein.

[0179] As shown in Figure 8 , Figure 8 The first feeding mechanism provided in some embodiments of the present application is shown in a simple structure diagram. The loss-in-weight scale can include a hopper 21, a stirring motor 22, a stirring paddle 23, a feeding motor 24, a feeding screw 25, a first scale platform 26, etc. The stirring motor 22 is used to drive the stirring paddle 23 to rotate, preventing the bridging of the powder mixture in the hopper 21 and causing uneven feeding. The feeding motor 24 drives the feeding screw 25 to rotate, conveying the powder mixture in the hopper 21, so that the powder mixture falls into the twin-screw machine. At the same time, the first scale platform 26 of the loss-in-weight scale can monitor the weight of the powder mixture in real time, and quantitatively control the amount of powder mixture.

[0180] The first feeding mechanism selects the loss-in-weight scale. The loss-in-weight scale can realize high-precision continuous quantitative feeding through static weighing, effectively ensuring the reliability, accuracy, and stability of the powder mixture feeding, and facilitating stable control of the ratio of the powder mixture and the solution, thereby ensuring the uniformity and consistency of the active substance mixture, and effectively improving the production quality of the battery.

[0181] According to some embodiments of the present application, the second feeding mechanism 30 is a metering pump.

[0182] The metering pump is a kind of fluid conveying machinery, which has the outstanding feature of maintaining constant flow regardless of discharge pressure, so as to convey the solution at a stable flow rate. The metering pump is a commonly used feeding mechanism for liquid conveying. The detailed structure of the metering pump is not limited or described herein.

[0183] As shown in Figure 9 , Figure 9 The second feeding mechanism provided in some embodiments of the present application is shown in a simple structure diagram. The metering pump includes a storage hopper 31, a metering hopper 32, a second scale platform 33, and a pump body 34. The liquid in the storage hopper 31 falls into the metering hopper 32, the metering hopper 32 is connected to the second scale platform 33, the liquid in the metering hopper 32 is stably pumped out through the pump body 34, and then enters the twin-screw machine through the discharge port 43.

[0184] The second feeding mechanism 30 selects the metering pump. The metering pump can convey the solution at a stable flow rate, effectively ensuring the reliability, accuracy, and stability of the solution feeding, and facilitating stable control of the ratio of the powder mixture and the solution, thereby ensuring the uniformity and consistency of the active substance mixture, and effectively improving the production quality of the battery.

[0185] According to some embodiments of the present application, please refer to Figures 10 to 12 , Figure 10A front view of an extrusion die provided for some embodiments of the present application; Figure 11 A structure diagram of a flow uniformizing plate provided for some embodiments of the present application; Figure 12 A top view of an extrusion die provided for some embodiments of the present application. The extrusion die 40 comprises a die body 41 and a flow uniformizing plate 45. The die body 41 is provided with an inlet 42, an outlet 43 and a material cavity 44 connecting the inlet 42 and the outlet 43. The flow uniformizing plate 45 is arranged in the material cavity 44. The flow uniformizing plate 45 divides the material cavity 44 into a first cavity connected with the inlet 42 and a second cavity connected with the outlet 43. The flow uniformizing plate 45 is provided with a plurality of through holes 451. The plurality of through holes 451 connect the first cavity and the second cavity.

[0186] As mentioned above, the extrusion die 40 can adopt a conventional plunger structure, a coat hanger structure, a fishtail structure, etc. The type of the extrusion die 40 can be different, and the shape of the material cavity 44 can also be different. The material cavity 44 is used to connect the inlet 42 and the outlet 43 and provide a buffer space for the active substance mixture.

[0187] The flow uniformizing plate 45 can be used to adjust the extrusion speed of the extrusion die 40 along the length direction of the outlet 43 (i.e. the width direction of the diaphragm). The plurality of through holes 451 on the flow uniformizing plate 45 can be arranged in rows. Each row of through holes 451 comprises a plurality of through holes 451 arranged at intervals along the length direction of the outlet 43. Of course, the plurality of through holes 451 on the flow uniformizing plate 45 can also be arranged in a matrix.

[0188] The flow uniformizing plate 45 can play a role in flow uniformization by controlling the size of the through holes 451. The flow uniformizing plate 45 can also play a role in flow uniformization by controlling the density of the through holes 451.

[0189] The shape of the through holes 451 can be circular, rectangular, triangular, etc. The present embodiment does not limit the shape of the through holes 451.

[0190] The flow uniformizing plate 45 can be integrally formed with the die body 41 or separately arranged with the die body 41 and assembled with the die body 41. For example, the outer circumferential surface of the die body 41 can be provided with a slot. The slot connects the material cavity 44 and the external space of the die body 41. The flow uniformizing plate 45 can be inserted into the slot to be detachably connected with the die body 41.

[0191] In some other embodiments, the flow uniformizing plate 45 can also be used to adjust the extrusion uniformity of the extrusion die 40 along the width direction of the outlet 43 (i.e. the thickness direction of the diaphragm) or other directions.

[0192] The flow equalizing plate 45 is arranged in the extrusion die 40, and the design of the flow equalizing plate 45 effectively adjusts the extrusion speed of the extrusion die 40, so that the extrusion speed of the active substance mixture along the length direction of the discharge port 43 is more uniform, thereby improving the uniformity of the extrusion of the active substance mixture along the length direction of the discharge port 43.

[0193] According to some embodiments of the present application, as shown in Figure 11 The diameter of the through hole 451 gradually increases from the middle to both sides of the flow equalizing plate 45 along the length direction of the discharge port 43.

[0194] It can be understood that the cross-sectional shape of the discharge port 43 corresponds to the cross-sectional shape of the final extruded film, and the extrusion die 40 of the present embodiment is used for extruding a film, and the length direction of the discharge port 43 extends along the width direction of the final extruded film.

[0195] That is, along the length direction of the discharge port 43, the smaller the diameter of the through hole 451 near the middle position of the flow equalizing plate 45, the larger the diameter of the through hole 451 near the both sides of the flow equalizing plate 45.

[0196] By limiting the change of the diameter of the through hole 451 to adjust the flow resistance of the active substance mixture, the active substance mixture can be distributed from the middle to both sides of the length direction of the discharge port 43, thereby reducing the risk that the flow rate of the active substance mixture is too large in the middle of the length direction of the discharge port 43 and the flow rate of the active substance mixture is too small on both sides of the length direction of the discharge port 43, thereby improving the uniformity of the extrusion of the active substance mixture along the length direction of the discharge port 43.

[0197] According to some embodiments of the present application, as shown in Figure 10 and Figure 12 The material cavity 44 includes a flow distribution area 441, a buffer area 442 and a pressure building area 443, which are arranged in sequence along the direction from the feed port 42 to the discharge port 43, the cross-sectional area of the flow distribution area 441 gradually increases from the feed port 42 to the buffer area 442, and the cross-sectional area of the pressure building area 443 gradually decreases from the buffer area 442 to the discharge port 43.

[0198] The flow distribution area 441 is in communication with the feed port 42, the cross-sectional area of the flow distribution area 441 gradually increases from the feed port 42 to the buffer area 442, the active substance mixture entering the material cavity 44 through the feed port 42 is gradually distributed in the flow distribution area 441, and the buffer area 442 gradually fills the material cavity 44, avoiding gaps in the active substance mixture. The cross-sectional area of the pressure building area 443 gradually decreases from the buffer area 442 to the discharge port 43, and the active substance mixture is extruded by the change of the cross-sectional area, so that the active substance mixture can be compacted, ensuring the density of the final extruded film, thereby effectively ensuring the structural uniformity and continuity of the extruded film.

[0199] It is understandable that the dimensions of the diversion zone 441 and the buffer zone 442 along the length of the discharge port 43 can be greater than the length of the discharge port 43, in order to ensure the structural compactness of the extruded film in its width direction and reduce the risk of problems such as voids or partial weakness in the film.

[0200] According to some embodiments of this application, the flow equalization plate 45 is disposed in the pressure building area 443 and / or the buffer area 442.

[0201] Specifically, one or more flow equalization plates 45 can be set. When one flow equalization plate 45 is set, it can be set in the pressure building zone 443 or in the buffer zone 442. For example, the flow equalization plate 45 can be set in the pressure building zone 443, so that the flow equalization plate 45 is close to the discharge port 43, thereby further ensuring the flow equalization effect of the flow equalization plate 45.

[0202] When multiple flow equalization plates 45 are provided, the multiple flow equalization plates 45 can be evenly spaced in the pressure building area 443, or evenly spaced in the buffer area 442, or at least one can be provided in the pressure building area 443 and at least one can be provided in the buffer area 442.

[0203] For example, there are two flow equalizers 45, one in the pressure building area 443 and the other in the buffer area 442.

[0204] The flow equalization plate 45 is set in the pressure building zone 443 and / or the buffer zone 442, which helps to further ensure the uniformity of the extrusion of the active material mixture along the length direction of the outlet 43.

[0205] Please refer to Figures 1 to 12 and further refer to Figures 13 to 15 , Figure 13 This is a schematic diagram of the overall structure of the electrode manufacturing equipment provided in some embodiments of this application; Figure 14 This is a simplified structural diagram of an electrode manufacturing apparatus provided in some embodiments of this application; Figure 15 for Figure 13 The image shows a partial enlarged view of part A. Some embodiments of this application also provide an electrode manufacturing apparatus 1000, which includes a film preparation device 100 and a composite device 200 as described in any of the above embodiments. The film preparation device 100 is used to extrude and form an active material film 500. The composite device 200 is disposed downstream of the film preparation device 100 and is used to composite a substrate 600 with the active material film 500 to form an electrode.

[0206] The composite device 200 is located downstream of the membrane preparation device 100, and combines the substrate 600 and the active material membrane 500 prepared by the membrane preparation device 100 to form an electrode.

[0207] There are various embodiments of the compounding device 200. For example, the compounding device 200 can include a rolling mechanism 220 and a unwinding mechanism 210. The rolling mechanism 220 can include at least one pair of rollers, and a compounding gap is formed between the rollers. The unwinding mechanism 210 can be arranged below the rolling mechanism 220, and is responsible for unwinding the substrate 600. The substrate 600 and the active material film 500 enter the compounding gap, and the rollers roll and compound the substrate 600 and the active material film 500.

[0208] As shown in FIG. 2, the rolling mechanism 220 includes three first rollers 221 arranged in sequence. In the conveying direction of the film, a first thinning gap is formed between the first first roller 221 and the second first roller 221, and a compounding gap is formed between the second first roller 221 and the third first roller 221. The first thinning gap can be used to thin the active material film 500. The thinned active material film 500 enters the compounding gap with the second roller, and the second first roller 221 and the third first roller 221 roll and compound the substrate 600 and the active material film 500. Figure 14

[0209] In some embodiments, the pole piece manufacturing apparatus 1000 can further include a thinning mechanism 230 arranged between the film preparation device 100 and the compounding device 200, to extrude and thin the film extruded by the film preparation device 100. As shown in FIG. 3, the thinning mechanism 230 can include two second rollers 231 rotating towards each other, and a second thinning gap is formed between the two second rollers 231. It can be understood that the width of the second thinning gap (corresponding to the thickness of the active material film) is greater than the width of the first thinning gap, so as to gradually thin the active material film 500. Figure 14

[0210] In other embodiments, please refer to FIG. 15, and further refer to FIGS. 16 and 17. Figure 16 Figure 17 Figure 16 FIG. 18 is a structural schematic diagram of a cutting mechanism provided in some embodiments of the present application; Figure 17 FIG. 19 is a structural schematic diagram of a rejecting mechanism provided in some embodiments of the present application. The pole piece manufacturing apparatus 1000 can further include an edge trimming device 300 arranged between the film extrusion device and the compounding device 200, for trimming the edges of the film, and at the same time, for changing the width of the film.

[0211] ​​​​Based on the embodiment that the composite device 200 comprises the rolling mechanism 220, the rolling mechanism 220 comprises three first pressing rollers 221, the trimming device 300 can cooperate with the first pressing roller 221 to reshape the film sheet. Specifically, the trimming device 300 comprises a cutting mechanism 310, the cutting mechanism 310 is used to abut against the first pressing roller 221 to cut the edge of the film sheet along the axial direction of the first pressing roller 221, so as to remove the edge of the film sheet in the width direction.

[0212] As shown in the example, Figure 16 The cutting mechanism 310 can comprise a base 311, a hob 312 and a first guide rail 313, the hob 312 is rotatably installed on the base 311, the hob 312 is used to cut the film sheet tangentially with the first pressing roller 221, and the base 311 is movably installed on the first guide rail 313 along the axial direction of the first pressing roller 221. The first guide rail 313 can also be provided with a first size measuring element 314, and the first size measuring element 314 is arranged on the first guide rail 313 along the axial direction of the first pressing roller 221. By adjusting the position of the base 311 on the first guide rail 313, the cutting width of the cutting mechanism 310 can be adjusted.

[0213] Among them, one base 311 can be arranged on the first guide rail 313, or two bases 311 can be arranged, and the two bases 311 are arranged along the axial direction of the first pressing roller 221 to cut the two sides of the film sheet in the width direction.

[0214] In addition, the trimming device 300 can also comprise a rejection mechanism 320, and the rejection mechanism 320 is distributed along the circumferential direction of the first pressing roller 221 and is spaced apart from the cutting mechanism 310, as shown in the example, Figure 17 The rejection mechanism 320 can comprise a blade 321, and the blade 321 is used to contact the first pressing roller 221 along the axial line thereof to peel off the cut edge adhered to the first pressing roller 221.

[0215] Corresponding to the cutting mechanism 310, the rejection mechanism 320 can comprise a second guide rail 322 and a blade 321, the blade 321 is movably installed on the second guide rail 322 along the axial direction of the first pressing roller 221 through a mounting seat, and the second guide rail 322 can also be provided with a second size measuring element 323, and the second size measuring element 323 is arranged on the second guide rail 322 along the axial direction of the first pressing roller 221, so as to accurately adjust the position of the blade 321.

[0216] Of course, based on the embodiment that two bases 311 are arranged on the first guide rail 313, two blades 321 can also be installed on the second guide rail 322, and the two blades 321 are arranged along the axial direction of the first pressing roller 221, and the two blades 321 correspond to the two hobs 312 one by one to cut and remove the edges of the two sides of the film sheet in the width direction.

[0217] In some embodiments, please refer to Figure 14 , and further refer to Figure 18 , Figure 18 The simple structure schematic diagram of the double-sided coating type pole piece manufacturing equipment provided by some embodiments of the present application is shown. The pole piece manufacturing equipment 1000 can also be of a double-sided coating type structure. Specifically, the pole piece manufacturing equipment 1000 can include two film piece preparation devices 100, and the compounding device 200 can include two roll pressing mechanisms 220. Based on the implementation form that the roll pressing mechanism 220 includes three first rollers 221 arranged in sequence, the two roll pressing mechanisms 220 can be oppositely arranged, and the two roll pressing mechanisms 220 correspond to the two film piece preparation devices 100 one by one. The first roller 221 and the second first roller 221 of each roll pressing mechanism 220 and the second first roller 221 and the third first roller 221 form roll pressing gaps therebetween, and the third first rollers 221 of the two roll pressing mechanisms 220 form a compounding gap therebetween, so that the film pieces are compounded on both surfaces of the substrate 600 in the thickness direction of the substrate 600.

[0218] In some embodiments, as shown in Figure 14 or Figure 18 , the pole piece manufacturing equipment 1000 further includes a drying device 400 arranged downstream of the compounding device 200 and responsible for drying the pole piece.

[0219] The pole piece manufacturing equipment includes the film piece preparation device 100 and the compounding device 200 arranged downstream of the film piece preparation device 100. The film piece preparation device 100 directly mixes and uniformly extrudes the powder mixture and the solution used for forming the active material layer into the active material film piece 500, and the compounding device 200 compounds the active material film piece 500 with the substrate 600 to obtain the pole piece. The overall pole piece manufacturing equipment 1000 has high integration and effectively improves the production quality and production efficiency of the pole piece.

[0220] Please refer to Figure 19 , Figure 19 The flowchart of the film piece preparation method provided by some embodiments of the present application is shown. Some embodiments of the present application provide a film piece preparation method, which mainly includes:

[0221] S1: mixing a first binder with a powder to form a powder mixture;

[0222] In this embodiment, the powder refers to the powder used for preparing the active material layer, which can include electrode active materials, conductive agents, etc. The first binder can be a fiberizable binder that is not easily dissolved in the solution, so as to increase the structural strength of the active material mixture and make the active material mixture form a muscle net structure, such as polytetrafluoroethylene, etc.

[0223] S2: dissolving a second binder in a solvent to form a solution;

[0224] In the present embodiment, the second binder can be used mainly to increase the flexibility and cohesiveness of the active substance mixture, and can be polyvinylidene fluoride or the like, and the solvent forming the solution can include small-molecule alcohols or esters.

[0225] S3: mixing the powder mixture and the solution to form an active substance mixture;

[0226] The powder mixture and the solution are mixed under the action of forces such as kneading, shearing, and stirring to form a dough-like active substance mixture having certain viscosity, flexibility, extensibility, and plasticity, so that the active substance mixture can be formed into a self-supporting film under subsequent extrusion pressure.

[0227] S4: extruding the active substance mixture into a film.

[0228] The dough-like active substance mixture formed by the above mixing is subjected to extrusion pressure, and under the constraint of the extrusion die 40 or other shaping structure, the active substance mixture is extruded into a three-dimensional structure of a belt-shaped film.

[0229] Please refer to Figures 1 to 9 Some embodiments of the present application provide a film preparation device 100, which comprises a mixing mechanism 10, a first feeding mechanism 20, a second feeding mechanism 30, and an extrusion die 40. The first feeding mechanism 20 is used to add a powder mixture containing powder and a first binder to the mixing mechanism 10, the second feeding mechanism 30 is used to add a solution containing a second binder to the mixing mechanism 10, the mixing mechanism 10 is used to mix the powder mixture and the solution, and the extrusion die 40 is connected to the discharge end of the mixing mechanism 10 and is used to extrude the film.

[0230] The mixing mechanism 10 is a double screw machine, the first feeding mechanism 20 is a loss-on-ignition balance, the second feeding mechanism 30 is a metering pump, the loss-on-ignition balance is arranged upstream of the metering pump along the conveying direction of the screw 11 of the double screw machine, and the extrusion die 40 is directly installed at the discharge end of the double screw machine.

[0231] The screw 11 of the double screw machine is composed of alternately arranged mixing rotor elements 114 and threaded conveying elements, wherein the threaded conveying elements include first threaded conveying elements 111, second threaded conveying elements 112, and third threaded conveying elements 113. The screw 11 includes multiple groups of mixing rotor conveying assemblies, each group of mixing rotor conveying assemblies includes two mixing rotor elements 114 and one second threaded conveying element 112 arranged in sequence along the conveying direction of the screw 11, the second threaded conveying element 112 is directly connected with the mixing rotor element 114, and the two mixing rotor elements 114 are connected with each other in mirror symmetry along the axis of the screw 11.

[0232] The screw rod 11 comprises six first threaded conveying elements 111, three groups of mixing rotor conveying assemblies, three first threaded conveying elements 111, two groups of mixing rotor conveying assemblies, four first threaded conveying elements 111, one second threaded conveying element 112 and four third threaded conveying elements 113 arranged in sequence along the conveying direction of the screw rod 11.

[0233] The outer diameter of the screw rod 11 is D, the pitch of the first threaded conveying element 111 is L1, the pitch of the second threaded conveying element 112 is L2, the pitch of the third threaded conveying element 113 is L3, the width of the screw ridge 1141 of the mixing rotor element 114 is d, the helix angle of the screw ridge 1141 of the mixing rotor element 114 is θ, and the thread groove depth of the first threaded conveying element 111, the second threaded conveying element 112 and the third threaded conveying element 113 is H, and the following conditions are met:

[0234] L1=1.0D, L2=0.6D, L3=0.4D, H=0.13D, d=0.06D, and R=120°.

[0235] It should be noted that the features in the embodiments of the present application can be combined with each other without conflict.

[0236] Although the present application has been described with reference to the preferred embodiments, various improvements can be made and parts thereof can be replaced with equivalents without departing from the scope of the present application. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A membrane preparation device, characterized by, The extrusion die is directly connected with the discharge end of the mixing mechanism. The first binder is a first type of binder which is not easily soluble in the solvent or has poor solubility in the solvent, and the second binder is a second type of binder which is soluble in the solvent.

2. The membrane preparation device of claim 1, wherein, The extrusion die is directly connected with the discharge end of the mixing mechanism.

3. The membrane preparation device of claim 1, wherein, The mixing mechanism is a double screw machine.

4. The membrane preparation device of claim 3, wherein, The screw of the double screw machine is composed of alternately arranged banbury rotor elements and threaded conveying elements.

5. The membrane preparation device of claim 4, wherein, The screw flight width of the banbury rotor element is d, and the outer diameter of the screw is D, 0.02D≤d≤0.15D.

6. The membrane preparation device of claim 5, wherein, 0.04D≤d≤0.1D.

7. The membrane preparation device of claim 4, wherein, The screw flight helix angle of the banbury rotor element is θ, 90°≤θ≤150°.

8. The membrane preparation device of claim 7, wherein, 110°≤θ≤130°.

9. The membrane preparation device of claim 4, wherein, The threaded conveying element includes a first threaded conveying element and a second threaded conveying element, the outer diameter of the screw is D, the pitch of the first threaded conveying element is L1, the pitch of the second threaded conveying element is L2, 0.8D≤L1≤1.2D, 0.5D≤L2≤0.8D.

10. The membrane preparation apparatus of claim 9, wherein, 0.9D≤L1≤1.1D, 0.6D≤L2≤0.7D.

11. The membrane preparation device of claim 9, wherein, The screw includes a plurality of banbury rotor conveying assemblies, each banbury rotor conveying assembly includes two banbury rotor elements and one second threaded conveying element arranged in sequence along the conveying direction of the screw, the second threaded conveying element is directly connected with the banbury rotor elements, and the two banbury rotor elements are connected in mirror image symmetry along the axis of the screw.

12. The membrane preparation device of claim 9, wherein, The threaded conveying element further includes a third threaded conveying element, the pitch of the third threaded conveying element is L3, 0.2D≤L3≤0.5D.

13. The membrane preparation device of claim 12, wherein, 0.3D≤L3≤0.45D.

14. The membrane preparation device of claim 12, wherein, The screw includes a first threaded conveying element, a banbury rotor conveying assembly, a first threaded conveying element, a banbury rotor conveying assembly, a first threaded conveying element, a second threaded conveying element and a third threaded conveying element arranged in sequence along the conveying direction of the screw.

15. The membrane preparation device of claim 4, wherein, The thread groove depth of the threaded conveying element is H, and the outer diameter of the screw is D, 0.1D≤H≤0.15D.

16. The membrane preparation device of claim 4, wherein, 0.12D≤H≤0.14D.

17. The membrane preparation apparatus of claim 3, wherein, The double screw machine includes a barrel and a screw, the screw is rotatably arranged in the barrel, and the gap between the outer circumferential surface of the screw and the inner wall of the barrel is L4, 0.1mm≤L4≤0.6mm.

18. The membrane preparation device of claim 17, wherein, 0.3mm≤L4≤0.5mm.

19. The membrane preparation apparatus of claim 3, wherein, The first feeding mechanism is located upstream of the second feeding mechanism along the conveying direction of the screw.

20. The membrane preparation device of claim 1, wherein, The first feeding mechanism is a loss-in-weight scale.

21. The membrane preparation device of claim 1, wherein, The second feeding mechanism is a metering pump.

22. The membrane preparation device of any one of claims 1-21, wherein, The extrusion die comprises a die body and a flow equalizing plate, the die body is provided with a material inlet, a material outlet and a material cavity communicating the material inlet and the material outlet, the flow equalizing plate is arranged in the material cavity, the flow equalizing plate divides the material cavity into a first cavity communicating with the material inlet and a second cavity communicating with the material outlet, the flow equalizing plate is provided with a plurality of through holes, and the plurality of through holes communicate the first cavity and the second cavity.

23. The membrane preparation device of claim 22, wherein, Along the length direction of the material outlet, the diameter of the through hole gradually increases from the middle of the flow equalizing plate to both sides.

24. The membrane preparation device of claim 22, wherein, The material cavity comprises a flow dividing zone, a buffer zone and a pressure building zone, the flow dividing zone, the buffer zone and the pressure building zone are arranged in sequence along the direction from the material inlet to the material outlet, the cross-sectional area of the flow dividing zone gradually increases from the material inlet to the buffer zone, and the cross-sectional area of the pressure building zone gradually decreases from the buffer zone to the material outlet.

25. The membrane preparation device of claim 24, wherein, The flow equalizing plate is arranged in the pressure building zone and / or the buffer zone.

26. An electrode tab manufacturing apparatus, characterized by, The film preparation device of any one of claims 1-25 is used for extruding a film; A compounding device is arranged downstream of the film preparation device, and is used for compounding a substrate and the film to form a pole piece. The film preparation device of any one of claims 1-25 is used for extruding a film; 27. A method of making a diaphragm, the method comprising: A first binder is mixed with a powder to form a powder mixture, the first binder is a first type of binder which is not easily soluble in a solvent or has poor solubility in the solvent; A second binder is dissolved in a solvent to form a solution, the second binder is a second type of binder which is soluble in the solvent; The powder mixture and the solution are mixed to form an active substance mixture; The active substance mixture is extruded into a film. ​

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