Electrode film, electrode sheet manufacturing method, and forming device

Abstract

The application provides a dry preparation method of an electrode film, material is distributed according to a preset weight and is limited in a corresponding area, and the material sequentially passes through a first stamping and a second stamping to obtain the electrode film, wherein the limitation is cancelled after the first stamping, and the first stamping and the second stamping are performed multiple times respectively; meanwhile, the application also provides a preparation method of an electrode sheet and an electrode sheet forming device for preparing the electrode sheet according to the dry preparation method of the electrode film and the preparation method of the electrode sheet. The electrode sheet forming device is used to prepare the electrode film, and the electrode film is hot-pressed and combined with a current collector to prepare the electrode sheet. The application effectively improves the uniformity of the electrode film and the electrical performance of the electrode sheet, realizes continuous production, has the advantages of high efficiency, stability and low cost, and is suitable for large-scale industrial application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrode membrane production equipment, and particularly to an electrode manufacturing method and a forming device. BACKGROUND

[0002] The cost and performance of lithium ion batteries (LIBs) depend largely on the manufacturing process of the electrodes. Currently, the electrodes of commercial LIBs are manufactured by slurry-casting (SC) procedure, i.e. a wet coating process, which limits the thickness of the electrodes. To overcome this limitation, solvent-free (SF) procedure, i.e. a dry manufacturing process, is a promising solution. SF process does not use solvent, and by dry homogenizing the binder with active material and conductive agent, it can manufacture thick electrodes without worrying about the uneven distribution of the binder, and thus has been widely used. However, there are still some problems to be solved in the current production process.

[0003] When preparing an electrode by SF process, generally, the conductive slurry (conductive additive, active material, binder) is first dry-mixed to form a fibrous mixture, and then the fibrous mixture is rolled into a supportable film material by a roller and transferred to a bonding station to roll and bond the film material with a current collector to form an electrode sheet. The most critical part of this preparation method is to roll the mixture into a supportable film material by a roller shaft and bond it with the current collector, so the quality of the film material and the tightness of the bonding with the current collector will greatly affect the quality of the electrode sheet. The common way to prepare the film material is to roll the mixture by a cylindrical roller shaft, so that the polymer crystals slip along the shear direction (c-axis) (as shown in FIG. 8), thereby forming a self-supporting film material. Although this rolling method is relatively simple, the fibrous mixture is easy to form cavities inside during the falling process, resulting in holes in the prepared film material, which further affects the uniformity of the film material and the performance of the film material. It may cause the film material to be too thick at the joint and prone to cracking and breaking. In addition, in actual operation, the factory equipment is often limited, and the equipment parameters need to be reset and adjusted every time the rolling is performed, which greatly reduces the efficiency. Therefore, how to solve the problems of easy breaking or over-thickness at the joint caused by multiple rollings and low production efficiency has become a hot spot of current research. SUMMARY

[0004] The present application provides a dry preparation method of electrode film, which is suitable for preparing electrode film with a thickness of 50 um or more, solves the quality problem caused by uneven thickness of the electrode film during rolling, and improves the production efficiency.

[0005] In a first aspect, the present application provides a dry preparation method of electrode film, comprising:

[0006] Firstly, the material is distributed according to a preset weight and limited in the corresponding area, and the material is sequentially subjected to a first stamping and a second stamping to obtain an electrode film, wherein the limitation is cancelled after the first stamping, and the first stamping and the second stamping are performed multiple times respectively.

[0007] The first stamping pressure increases to a first maximum pressure with the number of times, and remains unchanged at the first maximum pressure, wherein the first maximum pressure is selected from 500-2000 Mpa; the second stamping pressure increases or remains unchanged with the number of times, the second stamping pressure increases with the number of times is called second stamping variable pressure, and the second stamping pressure remains unchanged with the number of times is called second stamping constant pressure; when the second stamping variable pressure remains unchanged after increasing to a second stamping variable maximum pressure with the number of times, it is called second stamping variable maximum pressure, wherein the second stamping variable maximum pressure is selected from 3000-8000 Mpa; the second stamping constant pressure is selected from 2500-4000 Mpa.

[0008] As a further scheme, the distribution mode is not limited in principle and includes but is not limited to any one or several of extrusion or / and powder delivery to realize the processing of different materials.

[0009] As a further scheme, the material is heated before the first stamping to enhance the thermal plastic slip property of the material.

[0010] As a further scheme, when the first stamping is heated, the temperature range is selected from 50-120℃.

[0011] As a further scheme, the number of times of the first stamping is greater than 10.

[0012] As a further scheme, the stamping frequency of the first stamping is selected from 10-1000 times / min, and the preferred stamping frequency is selected from 50-200 times / min.

[0013] As a further scheme, the first stamping pressure is selected from 1-2000 Mpa.

[0014] As a further scheme, the first stamping pressure increases with the number of times in principle without limitation, for example, it can be X n+1 =d(X n ) m and other functions or self-set pressure values, wherein X represents the value of the first stamping pressure, d is selected from 1-9.9, m is selected from 1-3, n represents the nth stamping, X is greater than or equal to 1, and the initial first pressure is greater than or equal to 1 Mpa.

[0015] As a further solution, the number of secondary stamping is greater than 5.

[0016] As a further solution, the frequency of secondary stamping is selected from 5-100 times / min, preferably 5-50 times / min.

[0017] As a further solution, the pressure of secondary stamping is selected from 50-8000 Mpa, preferably 300-8000 Mpa, as the number of stamping increases.

[0018] As a further solution, the pressure of secondary stamping as the number of stamping increases is not limited in principle, for example, it can be Y p+1 =f(Y p ) q and other functions or self-set pressure values, wherein, wherein Y represents the value of the pressure of secondary stamping, f is selected from 1-9.9, q is selected from 1-3, p represents the pth stamping, Y is greater than or equal to 1, and the initial pressure of secondary stamping is greater than or equal to 1 Mpa.

[0019] As a further preferred solution, the initial pressure of secondary stamping is selected from 50-500 Mpa.

[0020] As a further preferred solution, the maximum pressure of secondary stamping is 3-10 times the maximum pressure of primary stamping.

[0021] As a further preferred solution, the constant pressure of secondary stamping is 2-8 times the maximum pressure of primary stamping.

[0022] As a further solution, the number of stamping in hot stamping is greater than 5.

[0023] As a further solution, the frequency of stamping in hot stamping is selected from 10-100 times / min, preferably 20-60 times / min.

[0024] As a further solution, the impact composite pressure in hot stamping can remain unchanged, or continuously or stepwise increase with the number of stamping.

[0025] As a further solution, the impact composite pressure in hot stamping is preferably selected to increase with the number of stamping, and when the impact composite pressure increases to the maximum impact composite pressure with the number of stamping, the impact composite pressure continues to remain unchanged at the maximum impact composite pressure with the remaining number of stamping, and the maximum impact composite pressure is selected from 800-1000 Mpa.

[0026] As a further solution, the impact composite pressure as the number of stamping increases in stamping is not limited in principle, for example, it can be Z a+1 =c(Za ) e and other functions or autonomously set pressure values, wherein, wherein Z represents the numerical value of the impact composite pressure, c is selected from 1-9.9, e is selected from 1-3, a represents the a-th stamping, Z is greater than or equal to 1, the initial impact composite pressure is greater than or equal to 1 MPa, and the initial impact composite pressure is selected from 10-300 MPa.

[0027] As a further scheme, when the impact composite pressure remains unchanged, the impact composite pressure is selected from 10-1000 MPa, preferably 50-350 MPa.

[0028] As a further scheme, when the hot pressing composite, the hot pressing composite pressure is selected from 50-1000 MPa, preferably 300-600 MPa.

[0029] As a further scheme, when the hot pressing composite, the temperature is selected from 80-300℃, and the heating time is selected from 1-60s.

[0030] As a further preferred scheme, when the hot pressing composite, the temperature is selected from 90-150℃, and the time is selected from 20-40s.

[0031] As a further preferred scheme, when the material is distributed in the partitioned area, a release layer is arranged on the corresponding area where the limiting is performed, the material is distributed on the release layer, and the release layer is heated and decomposed after the hot stamping is completed.

[0032] As a further scheme, in the preparation method of the pole piece, the temperature for heating and decomposing the release layer is selected from 130-300℃, and the time is selected from 1-60s.

[0033] As a further preferred scheme, the temperature for heating and decomposing the release layer is selected from 130-180℃, and the time is selected from 20-40s, which is helpful to further optimize the separation effect of the pole piece and protect the performance of the pole piece.

[0034] In a third aspect, the present scheme provides a pole piece forming device, comprising a material conveying belt, and a release layer pasting device, a material distribution device, a material heating device, a first-stage stamping device, a second-stage stamping device, a hot stamping device, and a heating release device arranged in sequence on the material conveying belt along the material conveying direction.

[0035] The pole piece forming device is further provided with a mold conveying assembly, comprising an electrode film mold, a mold conveying belt, a mold placing device, and a mold recycling device. The mold placing device is used to place the electrode film mold on the material conveying belt before the material distribution device. The mold conveying belt is arranged at the two side edges of the material conveying belt and is parallel to or higher than the material conveying belt in the horizontal direction. The mold conveying belt is used to carry the electrode film mold to pass through the material distribution device, the material heating device, and the first-stage stamping device in sequence. The mold recycling device is used to recycle the electrode film mold after the first-stage stamping.

[0036] The pole piece forming device is also provided with a current collector unwinding device and a pole piece winding device. The unwinding device is used to unwind the current collector and combine it with the electrode film passing through the hot stamping device. The pole piece winding device is used to wind the pole piece demolded by the hot stamping device.

[0037] The type of demolding layer pasting device is not limited, and a technician can select different pasting devices to paste the demolding layer to the surface of the material conveying belt according to needs

[0038] As a further scheme, the thickness of the demolding layer is selected from 0.1 μm-20 μm

[0039] As a further scheme, the demolding layer comprises a carrier layer and a glue layer arranged on any one side of the carrier layer.

[0040] As a further scheme, the material of the carrier layer is not limited in principle, and a technician can select substances including but not limited to one or more of polyethylene, polypropylene, and polycarbonate.

[0041] As a further scheme, the material of the glue layer is not limited in principle, and a technician can select substances including but not limited to one of polyacrylate glue and polyurethane glue.

[0042] As a further scheme, when the horizontal direction of the mold conveying belt is higher than that of the material conveying belt, the height is selected from 0.5-1 mm.

[0043] As a further scheme, the distributing device comprises a distributing port and a material tank, the material tank is fixedly connected with the distributing port, and the distributing port can distribute the material according to a preset weight.

[0044] As a further scheme, the primary stamping device comprises a primary punch and a primary stamping base, the primary stamping base is fixedly connected with the primary punch, the primary punch protrudes from the primary stamping base, the shape of the primary punch is matched with the electrode film mold, and the primary punch is used to perform primary stamping on the material in the electrode film mold.

[0045] As some examples, the electrode film mold comprises a primary electrode film grid, the primary electrode film grid is communicated with the front and back surfaces of the electrode mold, and the width is matched with the material conveying belt, the primary punch is matched with the primary electrode film grid, and the size of the primary punch is smaller than that of the primary electrode film grid by 0.8 mm-1.2 mm.

[0046] As a further solution, the primary punch is divided into primary punching blocks by longitudinal and transverse grooves, the electrode film mold comprises tab parts and partition parts, the tab parts and the partition parts are arranged in a staggered manner, and the primary electrode film grid is divided into electrode film grids by the tab parts and the partition parts. The electrode film grid is matched with the primary punching block, and the size of the primary punching block is smaller than the size of the electrode film grid by 0.8mm-1.2mm.

[0047] As a further solution, the primary punching base is further provided with a positioning protruding column matched with the electrode film mold.

[0048] As a further solution, the electrode mold is further provided with a positioning hole matched with the positioning protruding column on the primary punching device. The positioning hole helps to match the positioning protruding column on the primary punching device, so as to realize accurate pairing of the electrode film grid and the primary punching block.

[0049] As a further solution, the number of positioning holes is greater than or equal to 2.

[0050] As a further preferred solution, the number of positioning holes is selected from 4-8.

[0051] The secondary punching device comprises a secondary punch and a secondary punching base, the secondary punching base is fixedly connected with the secondary punch, and the secondary punch protrudes from the secondary punching base as a whole.

[0052] The electrode film mold is further provided with a positioning part, which is arranged on the left side and the right side of the electrode film mold.

[0053] The mold conveying belt is provided with positioning cards, the positioning cards are arranged in pairs to form a clamping groove matched with the positioning part of the electrode film mold, and the positioning part is clamped in the clamping groove formed by the positioning cards, so as to realize fixation of the electrode film mold on the mold conveying belt.

[0054] As a further solution, the electrode film mold is further provided with a placing handle, the placing handle is arranged on the left side and the right side of the electrode film mold respectively, and the number of the placing handles is greater than or equal to 2.

[0055] As a further preferred solution, the number of the placing handles is selected from 2-4.

[0056] The mold placing device comprises a placing holding arm and a first supporting base, the placing holding arm is matched with the placing handle of the electrode film mold, and the first supporting base is detachably connected with the placing holding arm.

[0057] As a further solution, the mold recycling device comprises a recycling clamping arm and a second supporting base, the recycling clamping arm is matched with the placing handle of the electrode film mold, and the second supporting base is detachably connected with the recycling clamping arm.

[0058] As a further solution, the current collector unwinding device comprises a current collector roll, a first roller pair, and a second roller pair, the current collector roll is used to unwind the current collector, and the second roller pair is used to guide the current collector compounded by the hot stamping device into the heating demolding device.

[0059] As a further solution, the electrode piece winding device comprises an electrode piece roll and a third roller pair, the third roller pair is used to guide the electrode piece through the heating demolding device, and the electrode piece roll is used to wind the electrode piece.

[0060] As a further solution, the electrode piece roll is provided with a current collector foil detector for detecting the current collector foil.

[0061] As a further solution, the electrode piece forming device is further provided with a controller for receiving instructions from technicians and controlling the operation of the electrode piece forming device.

[0062] Advantages

[0063] Compared with the prior art, the present application has at least the following advantages:

[0064] (1) By pre-setting the weight partition and limiting, the requirement for uniformity of feeding is reduced. The feeding form can be powder or dough-like material, and the feeding methods include screw extrusion, air pressure or push rod extrusion, powder blowing, etc., which can be applied. Each material compartment is quantitatively fed according to weight, which further ensures the consistency of the prepared electrode piece and improves the stability of product quality.

[0065] (2) The combination of primary stamping and secondary stamping is adopted, the primary stamping makes the material slip and flatten within the limiting range, prevents the local hardening of the material, avoids the generation of high stress concentration on the material surface, and reduces the risk of material rupture or irreversible change. The secondary stamping further makes the material slip and thin, eliminates the problem of peripheral protrusion caused by the primary stamping, and finally obtains an electrode film with good uniformity and high consistency.

[0066] (3) By hot stamping and compounding, the current collector and the solid electrode film are deformed slightly by stamping and compounding, and then the binder in the electrode film is bonded with the current collector by hot pressing, which realizes better combination of the electrode film and the current collector. This process optimizes the resistance and cycle performance of the electrode piece, and improves the electrical performance of the electrode piece.

[0067] (4) By setting the demolding layer, the problem of bonding and separation of the electrode film and the conveying belt is effectively solved, the damage of the electrode film or the wear of the conveying belt caused by bonding is avoided, the service life of the equipment is prolonged, and the production efficiency is improved.

[0068] (5) The whole process is continuous and simple, which can realize continuous production, improve the production efficiency, reduce the production cost, and is suitable for large-scale industrial production. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 This is a schematic diagram of an electrode forming device; Figure 2 This is a top view of the electrode forming device; Figure 3 This is a schematic diagram of an electrode film mold;

[0071] Figure 4 A schematic diagram of an electrode film mold placed on a mold conveyor belt; Figure 5 This is a schematic diagram of a primary stamping device; Figure 6 This is a schematic diagram of a two-stage stamping device; Figure 7 Figure 8 is a schematic diagram of the electrode forming process; Figure 9 is a schematic diagram of the slip deformation of polymer crystals under shear.

[0072] Figure 9 shows the slicing waste; Figure 10 This is a schematic diagram of the fabric distribution device. Figure 11 middle Figure 11 a represents the mold placement device 173. Figure 11 b represents the mold recycling device 174.

[0073] Among them, 11-material conveyor belt; 12-demolding layer pasting device; 13-material feeding device; 131-material feeding port; 132-material tank; 14-material heating device; 15-first-stage stamping device; 151-first-stage punch; 152-first-stage stamping base; 153-positioning protrusion; 16-second-stage stamping device; 161-second-stage punch; 162-second-stage stamping base; 17-mold conveying assembly; 171-mold conveyor belt; 1711-positioning clip; 172-electrode film mold; 1721-electrode film grid; 1722-electrode tab; 1723-positioning part; 1724- Positioning hole; 1725 - Handle placement; 1726 - Partition section; 173 - Mold placement device; 1731 - Holding arm placement; 1732 - First support base; 174 - Mold recycling device; 1741 - Recycling clamping arm; 1742 - Second support base; 21 - Current collector unwinding device; 211 - Current collector roll; 212 - First roller pair; 213 - Second roller pair; 22 - Hot stamping device; 221 - Hot stamping punch; 222 - Hot stamping body; 23 - Heating demolding device; 24 - Electrode winding device; 241 - Electrode roll; 242 - Third roller pair. Detailed Implementation

[0074] For the convenience of understanding, the present application will be described more fully below, and embodiments of the present application will be given, but the scope of the present application is not limited thereby.

[0075] The following is a description of terms or words, and unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the present application belongs.

[0076] In this paper, the term "material" refers to the raw material for preparing the electrode film, which can include both directly mixed raw materials and fiberized materials after mixing.

[0077] In this paper, "fiberized material" refers to electrode material after fiberization treatment in the process of dry preparation of electrode.

[0078] In this paper, the term "partitioning" refers to placing a predetermined amount of material into the center of each electrode sheet slice area according to the electrode sheet slice specifications.

[0079] In this paper, the term "hot stamping" refers to a process in which the electrode sheet and the electrode film are combined together by stamping and hot pressing during the electrode sheet processing.

[0080] In this paper, the term "stamping" refers to a process in which the current collector and the electrode film are combined together by mechanical stamping during the electrode sheet processing.

[0081] In this paper, the term "hot pressing" refers to a process in which the electrode sheet and the electrode film are combined together under high temperature conditions by heating and pressure during the electrode sheet processing.

[0082] In a first aspect, the present application provides a dry preparation method of an electrode film, comprising:

[0083] First, the material is partitioned according to the preset weight and the material is limited in the corresponding area, and the material is sequentially subjected to primary stamping and secondary stamping to obtain the electrode film, wherein the limitation is cancelled after primary stamping, and primary stamping and secondary stamping are performed multiple times, respectively.

[0084] The primary stamping pressure increases with the number of times to the primary maximum pressure, and remains unchanged at the primary maximum pressure, wherein the primary maximum pressure is selected from 500-2000 Mpa; the secondary stamping pressure increases with the number of times or remains unchanged, increases with the number of times is called secondary stamping variable pressure, and remains unchanged with the number of times is called secondary stamping constant pressure; when the secondary stamping variable pressure remains unchanged after increasing with the number of times to the maximum value of the secondary stamping variable pressure, it is called the maximum pressure of the secondary stamping variable pressure, wherein the maximum pressure of the secondary stamping variable pressure is selected from 3000-8000 Mpa; the secondary stamping constant pressure is selected from 2500-4000 Mpa.

[0085] In a second aspect, as Figure 7 The application provides a method for preparing a pole piece, comprising: covering a current collector on the surface of a prepared electrode film, hot stamping and slicing to obtain a pole piece.

[0086] To optimize the pole piece preparation process and improve production efficiency, the application provides a method for preparing a pole piece, which comprises: distributing and limiting materials according to a preset weight, combining primary stamping and secondary stamping to prepare an electrode film, then hot stamping the electrode film and the current collector, and slicing to obtain the pole piece. In the present application, the weight of the material is first preset, and the distribution and limitation are combined to ensure uniform distribution of the material and accurate weight control. The limitation refers to limiting the material within the predetermined pole piece area to avoid uneven distribution of the material in the subsequent stamping process, ensure the consistency of the electrode film, and avoid differences in electrical performance caused by uneven material. After the primary stamping is completed, the limitation is cancelled, so that the secondary stamping can stamp the material after the primary stamping, thereby improving the uniformity and density of the electrode film. In addition, in the present application, the primary stamping and the secondary stamping are combined. First, the material is flattened within the limit range by primary stamping to prevent excessive pressure from causing local hardening of the material and to avoid excessive stress concentration on the surface of the material, thereby reducing the risk of material rupture or irreversible change. Then, the secondary stamping is cancelled and performed again to further thin the material and eliminate the peripheral protrusion problem caused by the primary stamping, thereby obtaining an electrode film with good uniformity and high consistency. In addition, by hot stamping, the material is first stamped and then hot-pressed. On the basis of using stamping to make the current collector and the solid electrode film deform slightly, the hot-pressing makes the adhesive in the electrode film and the current collector adhere, thereby realizing better combination of the electrode film and the current collector, optimizing the pole resistance and cycle performance.

[0087] As some examples, the distribution mode is not limited in principle and includes, but is not limited to, any one or several of extrusion or / and powder delivery to realize the treatment of different materials.

[0088] As some examples, the material is heated before the primary stamping to enhance the thermoplastic sliding property of the material.

[0089] As some examples, when the primary stamping is heated, the temperature range is selected from 50-120°C.

[0090] As some examples, the number of primary stamping is greater than 10.

[0091] As some examples, the first level of pressing frequency is selected from 10-1000 times / min, preferably from 50-200 times / min. The pressing frequency will affect the flow rate of the material, and further affect the uniformity and consistency of the electrode film, and further affect the ion migration efficiency of the electrode sheet and the battery impedance. When the pressing frequency is selected from 50-200 times / min, it helps to promote the uniform distribution of the material, improve the uniformity and consistency of the electrode film, thereby reducing the electrode resistance and optimizing the performance of the electrode sheet.

[0092] As some examples, the first level of pressing pressure is selected from 1-2000 Mpa.

[0093] As some examples, the first level of pressing pressure increases with the number of times, which is not limited in principle, for example, it can be X n+1 = d(X n ) m and other functions or self-set pressure values, wherein X represents the value of the first level of pressing pressure, d is selected from 1-9.9, m is selected from 1-3, n represents the nth time of pressing, X is greater than or equal to 1, and the initial first level of pressing pressure is greater than or equal to 1 Mpa.

[0094] As some examples, the second level of pressing is more than 5 times.

[0095] As some examples, the second level of pressing frequency is selected from 5-100 times / min, preferably from 5-50 times / min.

[0096] As some examples, the second level of pressing pressure increases with the number of times, and the second level of pressing pressure is selected from 50-8000 Mpa, preferably from 300-8000 Mpa.

[0097] As some examples, the second level of pressing pressure increases with the number of times, which is not limited in principle, for example, it can be Y p+1 = f(Y p ) q and other functions or self-set pressure values, wherein Y represents the value of the second level of pressing pressure, f is selected from 1-9.9, q is selected from 1-3, p represents the pth time of pressing, Y is greater than or equal to 1, and the initial second level of pressing pressure is greater than or equal to 1 Mpa.

[0098] As some preferred examples, the initial second level of pressing pressure is selected from 50-500 Mpa.

[0099] As some preferred examples, the maximum pressure of the second-stage stamping variable pressure is 3-10 times the maximum pressure of the first stage, and the constant pressure of the second-stage stamping is 2-8 times the maximum pressure of the first stage. By controlling the relationship between the maximum pressure of the first stage and the constant pressure of the second-stage stamping and the maximum pressure of the second-stage stamping variable pressure, the electrode film formed after the first-stage stamping can be more effectively compacted, thereby eliminating local protrusions or uneven areas generated during the first-stage stamping process, further reducing the porosity of the electrode film, and improving the structural stability of the electrode film.

[0100] As some examples, during the hot stamping, stamping compounding is first performed, and after the stamping compounding is completed, hot compounding is performed. By means of stamping compounding and hot compounding, on the basis of realizing the preliminary combination of the electrode film and the current collector, the combination strength between the two can be further enhanced by using heat, the contact between the electrode film and the current collector is ensured to be more close, the interface defects are reduced, and the product cycle, impedance and other performances are optimized.

[0101] As some examples, during the stamping compounding, the number of stamping compounding is greater than 5.

[0102] As some examples, during the stamping compounding, the stamping compounding frequency is selected from 10-100 times / min, and is preferably 20-60 times / min.

[0103] As some examples, during the stamping compounding, the impact compounding pressure can remain unchanged or continuously or stepwise increase with the number of stamping compounding.

[0104] As some examples, during the stamping compounding, the impact compounding pressure is preferably selected to increase with the number of stamping compounding, and when the impact compounding pressure increases to the maximum impact compounding pressure with the number of stamping compounding, the impact compounding pressure continues to remain unchanged at the maximum impact compounding pressure with the remaining number of stamping compounding, and the maximum impact compounding pressure is selected from 800-1000 Mpa.

[0105] As some examples, during the stamping compounding, the impact compounding pressure that increases with the number of stamping compounding is not limited in principle, for example, it can be Z a+1 =c(Z a ) e and other functions or self-set pressure values, wherein, wherein Z represents the value of the impact compounding pressure, c is selected from 1-9.9, e is selected from 1-3, a represents the a-th stamping, Z is greater than or equal to 1, and the initial impact compounding pressure is greater than or equal to 1 Mpa, and the initial impact compounding pressure is selected from 10-300 Mpa.

[0106] As some examples, when the impact compounding pressure remains unchanged, the impact compounding pressure is selected from 10-1000 Mpa, and is preferably 50-350 Mpa.

[0107] As some examples, the hot-pressing composite pressure is selected from 50-1000 Mpa, preferably 300-600 Mpa.

[0108] As some examples, the hot-pressing composite temperature is selected from 80-300℃, and the heating time is selected from 1-60 s.

[0109] As some preferred examples, the hot-pressing composite temperature is selected from 90-150℃, and the heating time is selected from 20-40 s, which helps to further promote the adhesion between the binder in the electrode film and the current collector, optimize the adhesion effect, and realize the effective combination of the electrode film and the current collector.

[0110] As some preferred examples, the corresponding area where the limiting is performed is provided with a release layer when the material is distributed, the material is distributed on the release layer, and the release layer is heated and decomposed after the hot stamping is completed. The presence of the release layer helps to realize the easy and rapid separation of the pole piece and the carrier (such as a conveying belt), thereby ensuring the quality of the pole piece and improving the production efficiency.

[0111] As some examples, in the preparation method of the pole piece, the temperature for heating and decomposing the release layer is selected from 130-300℃, and the time is selected from 1-60 s.

[0112] As some preferred examples, the temperature for heating and decomposing the release layer is selected from 130-180℃, and the time is selected from 20-40 s, which helps to further optimize the separation effect of the pole piece and protect the performance of the pole piece.

[0113] In a third aspect, a pole piece forming device is provided. Figures 1-2 The pole piece forming device further comprises a mold conveying assembly 17, which comprises an electrode film mold 172, a mold conveying belt 171, a mold placing device 173, and a mold recycling device 174. The mold placing device 173 is used to place the electrode film mold 172 on the material conveying belt 11 before the material distributing device 13. The mold conveying belt 171 is arranged on both sides of the material conveying belt 11 and is parallel to or higher than the material conveying belt 11 in the horizontal direction. The mold conveying belt 171 is used to carry the electrode film mold 172 to pass through the material distributing device 13, the material heating device 14, and the primary stamping device 15 in sequence. The mold recycling device 174 is used to recycle the electrode film mold 172 after the primary stamping.

[0114] The pole piece forming device further comprises a mold conveying assembly 17, which comprises an electrode film mold 172, a mold conveying belt 171, a mold placing device 173, and a mold recycling device 174. The mold placing device 173 is used to place the electrode film mold 172 on the material conveying belt 11 before the material distributing device 13. The mold conveying belt 171 is arranged on both sides of the material conveying belt 11 and is parallel to or higher than the material conveying belt 11 in the horizontal direction. The mold conveying belt 171 is used to carry the electrode film mold 172 to pass through the material distributing device 13, the material heating device 14, and the primary stamping device 15 in sequence. The mold recycling device 174 is used to recycle the electrode film mold 172 after the primary stamping.

[0115] The pole piece forming device is further provided with a current collector unwinding device 21 and a pole piece winding device 24, the unwinding device 21 is used to unwind the current collector and combine it with the electrode film passing through the hot stamping device 22, and the pole piece winding device 24 is used to wind the pole piece demolded by the hot stamping device 22.

[0116] In the scheme, the demolding layer pasting device 12 can paste the demolding layer to the surface of the material conveying belt 11, the mold placing device 173 places the electrode film mold 172 on the material conveying belt 11 to which the demolding layer is pasted, and the distributing device 13 distributes the material into the electrode film mold 172 in a partitioned manner according to a preset weight, and the material is limited by the electrode film mold 172, and then the material heating device 14 heats the material, and the arrangement of the material heating device 14 helps to improve the thermal plastic slip property of the material by temperature, so that the material is more uniformly distributed in the primary stamping process.

[0117] After the heated material enters the working range of the stamping device 15 and is subjected to primary stamping, the mold recycling device 174 recycles the electrode film mold 172, the secondary stamping device 16 performs secondary stamping on the material subjected to primary stamping, and after the stamping is completed, the electrode film is obtained.

[0118] The current collector is covered on the surface of the prepared electrode film by the current collector unwinding device 21, and the electrode film and the current collector are hot stamped together by the hot stamping device 22, and then the electrode film is physically separated from the material conveying belt 11 by the heating demolding device 23, the heating demolding device 23 with the heating function realizes easy physical separation between the electrode film and the conveying belt, improves the production efficiency, and after demolding, the pole piece winding device 24 winds it to obtain a single-sided pole piece.

[0119] The demolding layer pasting device 12 is not limited in type, and a skilled person can select different pasting devices to paste the demolding layer to the surface of the material conveying belt 11 according to requirements.

[0120] As some examples, the demolding layer thickness is selected from 0.1 μm-20 μm, including a carrier layer and a glue layer arranged on any one side of the carrier layer. In order to avoid the influence of the demolding layer on the performance of the pole piece, a substance with a melting point higher than the hot stamping temperature and lower than the upper limit of the tolerance temperature of each substance in the material, and with no by-reaction with the battery material or electrolyte after shrinking or decomposing, is selected as the demolding layer. Therefore, the materials of the carrier layer and the glue layer in the demolding layer are not limited in principle, wherein the carrier layer can be selected from one or more of polyethylene, polypropylene, and polycarbonate; and the glue layer can be selected from one of polyacrylate glue and polyurethane glue.

[0121] As some examples, the mold conveying belt 171 is higher than the material conveying belt 11 in the horizontal direction, and the height is selected from 0.5-1 mm.

[0122] As some examples, the material distribution device 13 comprises a material distribution port 131 and a material tank 132, the material tank 132 is fixedly connected with the material distribution port 132, and the material distribution port 131 can distribute the material according to a preset weight.

[0123] As some examples, as shown in Figure 5 , the primary punching device 15 comprises a primary punch 151 and a primary punching base 152, the primary punching base 152 is fixedly connected with the primary punch 151, the primary punch 151 protrudes from the primary punching base 152, and the shape of the primary punch 151 is matched with the electrode film mold 172, which is used for primary punching the material in the electrode film mold 172.

[0124] As some examples, the electrode film mold 172 comprises a primary electrode film grid, which is communicated with the front and back surfaces of the electrode film mold 172 and has a width matched with the material conveying belt 11, the primary punch 151 is matched with the primary electrode film grid, and the size of the primary punch 151 is smaller than the size of the primary electrode film grid by 0.8mm-1.2mm.

[0125] As some preferred examples, as shown in Figure 3 , Figure 5 , the primary punch 151 is divided into primary punching blocks 1511 by longitudinally and transversely distributed grooves, the electrode film mold 172 comprises lug portions 1722 and partition portions 1726, the lug portions 1722 and the partition portions 1726 are longitudinally and transversely staggered to divide the primary electrode film grid into electrode film grids 1721, the electrode film grids 1721 are matched with the primary punching blocks 1511, and the size of the primary punching blocks 1511 is smaller than the size of the electrode film grids 1721 by 0.8mm-1.2mm. The existence of the electrode film grids 1721 can realize the limiting of the material in the corresponding area, and the cooperation with the material distribution device 13 can realize the consistency control of the electrode film, so that the electrode film with high consistency and good uniformity is obtained; the electrode film grids 1721 are matched with the primary punching blocks 1511 on the primary punching device 15, and the lug portions 1722 are arranged between two adjacent rows of electrode film grids 1721 to reserve lug space for subsequent electrode film preparation.

[0126] As some examples, the primary punching base 152 is further provided with a positioning convex column 153 matched with the electrode film mold 172.

[0127] As some examples, the electrode film mold 172 is further provided with a positioning hole 1724 matched with the positioning convex column 153 on the primary punching device 15, and the existence of the positioning hole 1724 is helpful for matching the positioning convex column 153 on the primary punching device 15 to realize the accurate pairing of the electrode film grid 1721 and the primary punching block 1511.

[0128] As some examples, the positioning holes 1724 are ≥2 in number.

[0129] As some preferred examples, the positioning holes 1724 are selected from 4-8 in number.

[0130] As shown in Figure 6 , the secondary punching device 16 comprises a secondary punch 161 and a secondary punching base 162, the secondary punching base 162 is fixedly connected with the secondary punch 161, and the secondary punch 161 protrudes from the secondary punching base 162 as a whole, which helps to provide more uniform secondary punching for the electrode film and remove the burr marks on the edges of the material after primary punching.

[0131] The electrode film mold 172 is also provided with positioning parts 1723 arranged on the left and right sides of the electrode film mold 172.

[0132] As shown in Figure 4 , the mold conveying belt 171 is provided with positioning cards 1711, which appear in pairs to form a card slot matched with the positioning parts 1723 of the electrode film mold 172, and the positioning parts 1723 are clamped in the card slot formed by the positioning cards 1711, so as to realize the fixation of the electrode film mold 172 on the mold conveying belt 171, avoid the displacement of the electrode film mold 172 and lose the limiting effect on the material, and improve the reliability and stability of the electrode piece forming device.

[0133] As some examples, the electrode film mold 172 is also provided with placing handles 1725, which are respectively arranged on the left and right sides of the electrode film mold 172, and the number of the placing handles 1725 is ≥2.

[0134] As some preferred examples, the number of the placing handles 1725 is selected from 2-4.

[0135] The mold placing device 173 comprises a placing holding arm 1731 and a first supporting base 1732, the placing holding arm 1731 cooperates with the placing handles 1725 of the electrode film mold 172 to place the electrode film mold 172 on the material conveying belt 11 between the demolding layer pasting device 12 and the material distributing device 13, and the first supporting base 1732 is detachably connected with the placing holding arm 1731.

[0136] As some examples, the mold recycling device 174 comprises a recycling clamping arm 1741 and a second supporting base 1742, the recycling clamping arm 1741 cooperates with the placing handles 1725 of the electrode film mold 172 to unload and recycle the electrode film mold 172 after primary punching from the material conveying belt 11, and the second supporting base 1742 is detachably connected with the recycling clamping arm 1741.

[0137] As some examples, the current collector unwinding device 21 comprises a current collector roll 211 for unwinding the current collector, a first roller pair 212 for covering the unwound current collector on the electrode film after secondary pressing, and a second roller pair 213 for guiding the current collector and the electrode film after compounding by the hot pressing device 22 into the heated demolding device 23.

[0138] As some examples, the pole piece winding device 24 comprises a pole piece roll 241 for winding the pole piece and a third roller pair 242 for guiding the pole piece through the heated demolding device 23.

[0139] As some examples, the pole piece roll 241 is provided with a current collector foil detector for detecting the current collector foil.

[0140] As some examples, the pole piece forming device is further provided with a controller for receiving instructions from technicians and controlling the operation of the pole piece forming device.

[0141] The pole piece forming device provided by the present application operates in a step-by-step manner, and the step time and interval can also be preset in the controller as needed. As an example, the specific working process is described as follows:

[0142] The pole piece forming device comprises the following procedures in the material conveying direction: a demolding layer pasting device 12 for pasting the demolding layer, a mold placing device 173 for placing an electrode film mold 172, a material distributing device 13 for distributing the material, a material heating device 14 for heating the material, a primary pressing device 15 for primary pressing the material, a mold recycling device 174 for recycling the electrode film mold 172 after primary pressing, a secondary pressing device 16 for secondary pressing the material, a hot pressing device 22 for hot pressing the electrode film and the current collector, and a heated demolding device 23 for heating and demolding the primary pole piece. The working position step intervals of the above procedures can be set to be the same, and the longest working time of the above procedures is selected as the step time of the material conveying belt 11.

[0143] The material is added to the material tank 132 of the material distributing device 13.

[0144] In one step time Δt n , the controller first controls the demolding layer pasting device 12 to paste the demolding layer on the material conveying belt 11.

[0145] In the next step time Δt n+1 , the mold placing device 173 places the electrode film mold 172 on the mold conveying belt 171 to which the demolding layer has been pasted, and the mold conveying belt 171 drives the electrode film mold 172 to travel synchronously with the material conveying belt 11.

[0146] At the next step time Δt n+2 Inside, the material conveyor belt 11 with the mold placement device 173 enters the partitioned material distribution position, and the material distribution device 13 places the preset material Mt n+2 (This refers to the object at step time Δt) n+2 The material M) that is laid on the material conveyor belt 11 by the material laying device 13 is laid in sections on the mold conveyor belt 171 with the release layer attached. The electrode film mold 172 plays a limiting role for the material in the area.

[0147] At the next step time Δt n+3 Inside, containing material Mt n+2 The material conveyor belt 11 enters the working position of the material heating device 14, and the material heating device 14 begins to heat the material Mt. n+2 , Enhanced material Mt n+2 Slippage;

[0148] At the next step time Δt n+4 Inside, the material Mt, heated by the material heating device 14 n+2 The material is conveyed by the material conveyor belt 11 into the working position of the primary stamping device 15, and the stamping device 15 begins to press the heated material Mt. n+2 During the first-stage stamping process, the stamping pressure increases with the number of stamping cycles and remains constant after reaching the maximum pressure of the first stage.

[0149] At the next step time Δt n+5 Inside, the mold recycling device 174 recovers the electrode film mold 172 from the material conveyor belt 11, thus eliminating the need for the mold recycling device 174 to process the material Mt after the first-stage stamping. n+2 The limiting function;

[0150] At the next step time Δt n+6 Inside, the material conveyor belt 11 drives the material Mt, which is released from the limit after the first-stage stamping. n+2 The material enters the working position of the secondary stamping device 16, where it undergoes secondary stamping. After stamping, the material Mt... n+2 Forming an electrode film;

[0151] At the next step time Δt n+7 Inside, the material conveyor belt 11 drives the material Mt n+2 The current collector unwound from the current collector unwinding device 21 is combined with the current collector in the hot stamping device 22. The hot stamping device 22 performs hot stamping on the electrode film and the current collector to achieve electrode film Mt n+6 After hot stamping, the material Mt is combined with the current collector. n+2 It forms a primary electrode with the current collector.

[0152] At the next step time Δt n+8 In the next step time Δt, the material conveying belt 11 drives the primary electrode sheet into the working position of the heating demolding device 23, and the heating demolding device 23 heats the primary electrode sheet and the corresponding material conveying belt 11, so that the demolding layer is decomposed, thereby realizing the separation of the primary electrode sheet and the material conveying belt 11, and obtaining the electrode sheet.

[0153] Finally, the current collector unwinding device 21 unwinds the current collector from the secondary electrode film Mt n+6 The electrode sheet winding device 24 winds the separated electrode sheet on the material conveying belt 11 to obtain the electrode sheet roll.

[0154] At the same time, each process can be synchronized at the respective working position within the same step time, thereby realizing the continuous preparation of the electrode sheet.

[0155] The electrode sheet prepared by the above steps is a single-sided electrode sheet. When a double-sided electrode sheet is needed, the single-sided electrode sheet winding tape is connected to the current collector unwinding device 21, the switch is turned on, and the above operation is repeated to obtain a double-sided electrode sheet roll. The double-sided electrode sheet roll is sliced to obtain the electrode sheet.

[0156] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and do not represent all possible embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0157] The chemical materials involved in the following examples and comparative examples are all prior art and are obtained by commercial purchase. The experimental devices, testing devices, etc. involved in the following examples and comparative examples are all conventional devices in the art, without special requirements and limitations.

[0158] Example 1

[0159] The material with a ratio of NCM ternary:CNT:PEFT:PVDF of 84:1:10:5 is stirred and premixed for 1 h, and is subjected to fiberization treatment by air fiberization for 2 h. A 10 μm single-sided polycarbonate film containing polyacrylate glue is used as the demolding layer, the step speed of the material conveying belt 11 is set to 1 min / time, the heating temperature is 90°C, the primary punching rate is 100 times / min, and the primary punching pressure is increased from small to large according to the rule X n+1 =5X n , wherein X1=0.2 Mpa, X≤1000 Mpa, and n represents the n th punching, and when n=7, the primary punching pressure is maintained at 1000 Mpa; the secondary punching rate is 20 times / min, and the secondary punching pressure is increased according to the rule Y q+1 =2Yq The rule is from small to large, wherein Y1=300Mpa and Y≤3000Mpa, when q=5, the second stamping pressure is maintained at 3000Mpa q represents the q-th stamping, when hot stamping, the impact composite pressure is 100Mpa, the stamping speed is selected from 40 times / min, when hot pressing, the hot pressing composite pressure is selected from 500Mpa, the hot pressing temperature is selected from 100℃, the hot pressing time is selected from 30s, when demolding, the demolding temperature is selected from 100℃, the demolding time is selected from 30s, and after the demolding time ends, it is rapidly reduced to room temperature.

[0160] The switch is opened, the release layer pasting device 12 pastes the single-sided polycarbonate film containing polyacrylate glue on the material conveying belt 11, the mold placing device 173 places the electrode film mold 172 on the mold conveying belt 17, the material distributing device 13 distributes the material into the electrode film mold 172, and then passes through the material heating device 14, the first-stage stamping device 15, the second-stage stamping device 16, the fluid unwinding device 21, the hot stamping device 22, the heating demolding device 23, and the electrode piece winding device 24. After winding 100 meters, the stop button is pressed, the electrode piece winding device 24 stops winding after detecting the current collector light foil, and a single-sided electrode piece is obtained.

[0161] The wound single-sided electrode piece is fed to the current collector unwinding device 21 and the tape is connected, the switch is turned on, and the above operation is repeated to complete the double-sided film production to obtain an electrode piece roll. The electrode piece roll is cut into slices and made into a battery.

[0162] Example 2

[0163] The preparation method is the same as that in Example 1, except that the first-stage stamping speed is 49 times / min, the material conveying belt 11 advances at a speed of 3 min / time, and the equipment is paused after all operations are completed, and then the work is continued after the material conveying belt 11 advances by one step.

[0164] Example 3

[0165] The preparation method is the same as that in Example 1, except that the second-stage stamping pressure is maintained unchanged during the second-stage stamping, and the second-stage stamping pressure is 3500Mpa.

[0166] Example 4

[0167] The preparation method is the same as that in Example 1, except that the impact composite pressure is 400Mpa during hot stamping.

[0168] Example 5

[0169] The preparation method is the same as that in Example 1, except that the hot pressing composite temperature is 180℃ during hot stamping.

[0170] Example 6

[0171] The preparation method is the same as Example 1, except that the temperature at the time of demolding is selected from 180°C.

[0172] Comparative Example 1

[0173] The same materials as in Example 1 are used, except that multiple roll pressing is used to form the film, in which the main roller pressure is 3000 MPa, and the film is rolled 13 times to obtain a single-sided electrode film with the same thickness as in Example 1. After the two-sided single-sided electrode film is prepared, the current collector is rolled to obtain a double-sided electrode film, which is cut into pieces to form a battery.

[0174] Comparative Example 2

[0175] The preparation method is the same as Example 1, except that the secondary stamping is not performed.

[0176] Comparative Example 3

[0177] The preparation method is the same as Example 1, except that the mold is not used.

[0178] Comparative Example 4

[0179] The preparation method is the same as Example 1, except that the hot stamping is not performed.

[0180] Comparative Example 5

[0181] The preparation method is the same as Example 1, except that only 5 primary stamping is performed.

[0182] Comparative Example 6

[0183] The preparation method is the same as Example 1, except that the primary stamping pressure is fixed and remains at 150 MPa.

[0184] Comparative Example 7

[0185] The preparation method is the same as Example 1, except that the secondary stamping rate is 200 times / min.

[0186] Comparative Example 8

[0187] The preparation method is the same as Example 1, except that the single-sided polyacrylate-containing poly carbonate film is not pasted as a demolding layer.

[0188] Comparative Example 9

[0189] The preparation method is the same as Example 1, except that only 3 stamping is performed during the secondary stamping.

[0190] Comparative Example 10

[0191] The preparation method is the same as Example 1, except that the hot stamping is performed at a hot pressing composite pressure of 10 MPa.

[0192] Comparative Example 11

[0193] The preparation method is the same as that in Example 1, except that the demolding temperature is selected from 65°C.

[0194] Test test

[0195] The ion impedance test equipment in the example is an Autolab Nova2.1 electrochemical workstation.

[0196] According to the active material quality and the material gram capacity, the design capacity of the sample battery cell made of the electrode sheet in the example is calculated to be 800 mAh, and the 1C cycle is performed by charging at 0.8 A (1C) CC-CV to 4.2 V and then discharging at 0.8 A to 2.7 V, and the discharge capacity of each cycle is recorded, and the discharge capacity of each cycle / the initial discharge capacity is the 1C cycle capacity retention rate.

[0197] The 2C / 0.33C capacity ratio test method is that the capacity obtained by charging at 0.8 A (1C) CC-CV to 3.95 V and discharging at 1.6 A to 2.7 V is the 2C capacity, the capacity obtained by charging at 0.8 A (1C) CC-CV to 3.95 V and discharging at 0.264 A (0.33C) to 2.7 V is the 0.33C capacity, and the 2C capacity / 0.33C capacity is the 2C / 0.33C capacity ratio.

[0198] The test results are shown in Table 1.

[0199] Table 1

[0200]

[0201]

[0202] From Examples 1-6 and Comparative Examples 1-11, it can be observed that Examples 1-6 exhibit better ion impedance, 2C / 0.33C capacity ratio, and 1C cycle 100 times capacity retention rate than Comparative Examples 1-11, and at the same time, the single-sided electrode film thickness difference of the examples (≤3) is also better than that of the comparative examples (≥5), which indicates that the electrode sheet prepared by the present scheme can effectively avoid the phenomenon of electrode film internal cavity, cracking or unevenness, thereby optimizing the electrode sheet resistance, improving the capacity retention capability, and optimizing the cycle performance.

[0203] From Example 1 and Comparative Example 1, it can be observed that when the electrode sheet is prepared by the multiple rolling method, the ion impedance, 2C / 0.33C capacity ratio, and 1C cycle 100 times capacity retention rate of Comparative Example 1 are all weaker than those of Example 1, which may be because, compared with the present scheme, Comparative Example 1 prepared by the multiple rolling method may have unevenness, thereby affecting the electrode sheet performance.

[0204] We further discuss the role of primary and secondary stamping in optimizing the scheme, from Example 1, Comparative Example 2 can be observed that when not to secondary stamping, Comparative Example 2 has uneven appearance, and far inferior to the performance of Example 1, indicating that primary and secondary stamping is essential for optimizing the electrode film structure and obtaining good performance of the electrode sheet.

[0205] In Comparative Example 3, we discuss the role of the electrode sheet mold. The presence of the electrode sheet mold realizes the control of the thickness and performance of the electrode sheet on the basis of realizing the preliminary shaping of the electrode film. When the electrode sheet mold is not used, Comparative Example 3 shows an irregular appearance, and the single-sided electrode film thickness is lower than that of Example 1, which further affects the capacity retention ability of the electrode sheet.

[0206] Similarly, hot pressing is also an important step in the scheme. In Comparative Example 4, we only stamp without hot pressing when the composite electrode film and the current collector are combined. At this time, the current collector falls off. This may be because the process of hot pressing helps to promote the adhesion of the adhesive in the electrode film and the current collector. Therefore, when hot pressing is not performed, the current collector falls off.

[0207] In Example 1, Comparative Examples 5-7, we discuss the influence of primary and secondary stamping conditions on the performance of the electrode film and the electrode sheet. It can be observed that Comparative Examples 5-7 all show worse ion impedance, 2C / 0.33C capacity ratio, and cycle capacity retention rate than Example 1. This indicates that the conditions of primary and secondary stamping (including stamping rate, stamping times, and stamping pressure) are also one of the factors affecting the electrode film and the electrode sheet. When the primary stamping frequency is not selected from 10-1000 times / min, the primary stamping pressure is not selected from 1-2000 Mpa, the secondary stamping frequency is not selected from 5-100 times / min, and the secondary stamping pressure is not selected from 50-8000 Mpa, the electrode film may appear uneven, thereby affecting the performance of the electrode sheet.

[0208] In Example 1, Comparative Example 8, we observe that the lack of release layer also affects the performance of the electrode film and the electrode sheet. Compared with Example 1, when no release layer is set (Comparative Example 8), the material is pressed on the conveying table and is difficult to physically separate under the action of primary and secondary stamping. After forced separation, Comparative Example 8 exhibits a serious cracking phenomenon.

[0209] In Example 1, Comparative Examples 9-10, we discussed the influence of the hot stamping conditions on the performance of the electrode sheet when the electrode film was combined with the current collector by hot stamping. It can be observed that when the stamping combination times were 3 or the hot stamping combination pressure was 10 MPa, the performance of the electrode sheet of Comparative Examples 9 and 10 was greatly affected, and the current collector of Comparative Example 10 directly fell off. This may be because too few stamping combination times (<5 times) and too low hot stamping combination pressure (<50 MPa) cannot guarantee the full adhesion of the current collector to the electrode film.

[0210] Furthermore, we also discussed the influence of the demolding temperature on the performance of the electrode sheet. When the demolding temperature was selected from 65°C, the electrode sheet prepared in Comparative Example 11 had a demolding layer adhered to the surface. This may be because the demolding temperature of 65°C cannot achieve the complete pyrolysis of the demolding layer, thereby affecting the results of Comparative Example 11.

[0211] The frequency of stamping will affect the flow rate of the material in the electrode sheet mold, and in turn affect the performance of the electrode film. From Examples 1-2, we can observe that when the first-stage stamping speed is selected from 100 times / min, Example 1 exhibits better ion impedance, capacity retention ability, and cycle performance than Example 2. This may be because when the stamping frequency is selected from 50-200 times / min, the material is more evenly distributed in the electrode sheet mold, thereby improving the performance of the electrode film and optimizing the electrode resistance. Therefore, Example 1 exhibits better performance.

[0212] When performing first-stage stamping and second-stage stamping, the stamping pressure is regularly increased from small to large, which helps to obtain an electrode film with better uniformity and mechanical strength, thereby optimizing the performance of the electrode sheet. Therefore, in Examples 1 and 3, we observe that Example 1, which changes according to the rule Y q+1 = 2Y q , Y1 = 300 MPa and Y≤3000 MPa, has better impedance and cycle performance than Example 3.

[0213] In this scheme, we realize the combination of the current collector and the electrode film by hot stamping. Therefore, in Examples 1, 4-5, we further explore the conditions during hot stamping. It can be observed that Example 1 exhibits better ion impedance, capacity retention ability, and cycle performance than Examples 4 and 5. This may be because stamping combination can cause the current collector and the solid-state electrode film to mutually deform slightly, thereby achieving high adhesion. Hot stamping combination can make the binder in the electrode film and the current collector adhere. When the stamping combination pressure is selected from 50-350 MPa and the hot stamping combination temperature is selected from 90-150°C, it helps to optimize the mechanical properties of the electrode sheet and further improve the adhesion strength between the electrode film and the current collector on the basis of realizing the full combination of the electrode film and the current collector, thereby optimizing the performance of the electrode sheet.

[0214] In order to realize the rapid physical separation of the pole piece and the material conveying belt 11, the scheme is provided with a demolding layer, which rapidly decomposes under certain temperature conditions, realizing the separation of the pole piece and the material conveying belt 11. Therefore, in examples 1 and 6, we discuss the different performances of the pole pieces brought by different demolding temperatures. It can be observed that, under the demolding temperature of 135 DEG C, example 1 exhibits better comprehensive performance than example 6. This may be because when the temperature for heating the demolding layer to separate is selected from 120-150 DEG C, the substances in the electrode film can be better protected, thereby improving the performance of the pole piece.

[0215] The technical features of the above-described examples can be combined in any manner. In order to make the description concise, all possible combinations of the technical features in the above-described examples are not described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure. Although the above has shown and described the embodiments of the present disclosure, it should be understood that the above-described examples are exemplary and should not be construed as limiting the present disclosure, and those skilled in the art can modify, modify, replace and deform the above-described examples within the scope of the present disclosure. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present disclosure and the features of the different embodiments or examples without contradiction.

Claims

1. A dry preparation method for an electrode film, characterized in that, The process includes the following steps: dividing the material into sections and limiting the material within the corresponding areas; the material is then subjected to a first-stage stamping and a second-stage stamping to obtain an electrode film. The limiting is removed after the first-stage stamping, and the number of first-stage stampings is greater than 10, while the number of second-stage stampings is greater than 5. The first-stage stamping pressure increases with each stamping cycle until it reaches the maximum pressure, then remains constant at that maximum pressure, which is selected from 500-2000 MPa. The second-stage stamping pressure either increases with each stamping cycle or remains constant; increasing with each stamping cycle is called the second-stage variable pressure, while remaining constant is called the second-stage constant pressure. When the second-stage variable pressure increases with each stamping cycle until it reaches its maximum value and then remains constant, it is called the second-stage variable maximum pressure, which is selected from 3000-8000 MPa. The second-stage constant pressure is selected from 2500-4000 MPa. During the second-stage stamping, the stamping frequency is selected from 5-100 times / min.

2. The dry preparation method of the electrode film according to claim 1, characterized in that, The material feeding method can be selected from extrusion or powder conveying, or any one or more of them.

3. The dry preparation method of the electrode film according to claim 1, characterized in that, The material is heated before the first-stage stamping.

4. The dry preparation method of the electrode film according to claim 1, characterized in that, When the primary stamping is heated, the temperature range is selected from 50-120℃.

5. The dry preparation method of the electrode film according to claim 1, characterized in that, During the first-stage stamping, the stamping frequency is selected from 10-1000 times / min.

6. The dry preparation method of the electrode film according to claim 1, characterized in that, During the first-stage stamping, the stamping frequency is selected from 50-200 times / min.

7. The dry preparation method of the electrode film according to claim 1, characterized in that, The primary stamping pressure is selected from 1-2000 MPa.

8. The dry preparation method of the electrode film according to claim 1, characterized in that, During the first-stage stamping, the increasing pressure pattern of the first-stage stamping with each stamping cycle is selected from X. n+1 =d(X n ) m Where X represents the value of the first-stage stamping pressure, d is selected from 1 to 9.9, m is selected from 1 to 3, n indicates that this stamping is the nth stamping, X is greater than or equal to 1, and the initial first-stage pressure is greater than or equal to 1 MPa.

9. The dry preparation method of the electrode film according to claim 1, characterized in that, During the secondary stamping process, the stamping frequency is selected from 5-50 times / min.

10. The dry preparation method of the electrode film according to claim 1, characterized in that, When the pressure of the secondary stamping transformer increases with the number of times, the pressure of the secondary stamping transformer is selected from 50-8000 MPa.

11. The dry preparation method of the electrode film according to claim 1, characterized in that, When the pressure of the secondary stamping transformer increases with the number of times, the pressure of the secondary stamping transformer is selected from 300-8000 MPa.

12. The dry preparation method of the electrode film according to claim 1, characterized in that, During the two-stage stamping process, the variation in pressure of the two-stage stamping process with increasing number of stamping cycles follows the pattern Y. p+1 =f(Y p ) q Where Y represents the value of the secondary stamping transformer pressure, f is selected from 1-9.9, q is selected from 1-3, p indicates that this stamping is the p-th stamping, Y is greater than or equal to 1, and the initial secondary stamping transformer pressure is greater than or equal to 1 MPa.

13. The dry preparation method of the electrode film according to claim 1, characterized in that, The initial secondary stamping pressure is selected from 50-500 MPa.

14. The dry preparation method of the electrode film according to claim 1, characterized in that, The maximum pressure of the secondary stamping transformer is 3-10 times that of the primary transformer.

15. The dry preparation method of the electrode film according to claim 1, characterized in that, The pressure of the secondary stamping constant pressure is 2-8 times that of the maximum pressure of the primary stamping.

16. A method for preparing an electrode sheet comprising the electrode film of claim 1, characterized in that, The process includes the following steps: covering the surface of the prepared electrode film with a current collector, hot stamping, and slicing to obtain an electrode sheet.

17. The method for preparing the electrode according to claim 16, characterized in that, During the hot stamping process, the number of stamping cycles is greater than 5.

18. The method for preparing the electrode according to claim 16, characterized in that, During the hot stamping process, the stamping composite frequency is selected from 10-100 times / min.

19. The method for preparing the electrode according to claim 16, characterized in that, During the hot stamping process, the stamping frequency is selected from 20-60 times / min.

20. The method for preparing the electrode according to claim 16, characterized in that, During hot stamping, the combined impact pressure can remain constant or increase continuously and stepwise with the number of stamping cycles.

21. The method for preparing the electrode according to claim 20, characterized in that, During the hot stamping process, the combined impact pressure increases with the number of stamping cycles. When the combined impact pressure increases to the maximum combined impact pressure, the combined impact pressure continues to remain constant at the maximum combined impact pressure with the remaining cycles. The maximum combined impact pressure is selected from 800-1000 MPa.

22. The method for preparing the electrode according to claim 20, characterized in that, During the stamping compounding process, the impact compounding pressure law that increases with the number of stamping compounding cycles is selected from Z. a+1 =c(Z a ) e Where Z represents the value of the impact composite pressure, c is selected from 1-9.9, e is selected from 1-3, a indicates that this stamping is the a-th stamping, Z is greater than or equal to 1, and the initial impact composite pressure is greater than or equal to 1 MPa.

23. The method for preparing the electrode according to claim 22, characterized in that, The initial impact composite pressure is selected from 10-300 MPa.

24. The method for preparing the electrode according to claim 20, characterized in that, When the combined impact pressure remains constant, the combined impact pressure is selected from 10-1000 MPa.

25. The method for preparing the electrode according to claim 20, characterized in that, When the combined impact pressure remains constant, the combined impact pressure is selected from 50-350 MPa.

26. The method for preparing the electrode according to claim 16, characterized in that, During the hot stamping process, the combined hot pressing pressure is selected from 50-1000 MPa.

27. The method for preparing the electrode according to claim 16, characterized in that, During the hot stamping process, the combined hot pressing pressure is selected from 300-600 MPa.

28. The method for preparing the electrode according to claim 16, characterized in that, During the hot stamping process, the hot pressing temperature is selected from 80-300℃, and the heating time is selected from 1-60s.

29. The method for preparing the electrode according to claim 16, characterized in that, During the hot stamping process, the hot pressing temperature is selected from 90-150℃, and the time is selected from 20-40s.

30. The method for preparing the electrode according to claim 16, characterized in that, When laying materials in sections, a release layer is provided on the corresponding area for limiting. After hot stamping, the release layer is separated by heating.

31. The method for preparing the electrode according to claim 16, characterized in that, In the method for preparing the electrode sheet, the temperature for heating and delamination of the demolding layer is selected from 130-300℃, and the time is selected from 1-60s.

32. The method for preparing the electrode according to claim 31, characterized in that, The temperature for heating and separating the demolding layer is selected from 130-180℃, and the time is selected from 20-40s.

33. An electrode forming apparatus, characterized in that, Electrode films are prepared by any one of the methods described in claims 1-15, or electrode sheets are prepared by any one of the methods described in claims 16-32; The electrode forming apparatus includes: Material conveyor belt (11), and on the material conveyor belt (11), a demolding layer pasting device (12), a material feeding device (13), a material heating device (14), a primary stamping device (15), a secondary stamping device (16), a hot stamping device (22), and a heating demolding device (23) are arranged sequentially along the material conveying direction. The electrode forming device is also provided with a mold conveying assembly (17), including an electrode film mold (172), a mold conveyor belt (171), a mold placement device (173), and a mold recycling device (174). The mold placement device (173) is used to place the electrode film mold (172) on the material conveyor belt (11) in front of the material feeding device (13). The mold conveyor belt (171) is set on both sides of the material conveyor belt (11) and is parallel to or higher than the material conveyor belt (11) in the horizontal direction. The mold conveyor belt (171) is used to transport the electrode mold (172) through the material feeding device (13), the material heating device (14), and the first-stage stamping device (15) in sequence. The mold recycling device (174) is used to recycle the electrode mold (172) after the first-stage stamping. The electrode forming device is further provided with a current collector unwinding device (21) and an electrode winding device (24). The unwinding device (21) is used to unwind the current collector so that it can be combined with the electrode film after being hot-pressed by the device (22). The electrode winding device (24) is used to wind up the electrode after being demolded by the hot-pressed device (22).

34. The electrode forming apparatus according to claim 33, characterized in that, The thickness of the release layer is selected from 0.1μm to 20μm.

35. The electrode forming apparatus according to claim 33, characterized in that, The release layer includes a carrier layer and an adhesive layer disposed on any side of the carrier layer.

36. The electrode forming apparatus according to claim 35, characterized in that, The carrier layer can be selected from one or more of polyethylene, polypropylene, and polycarbonate.

37. The electrode forming apparatus according to claim 35, characterized in that, The adhesive layer is made of either polyacrylate adhesive or polyurethane adhesive.

38. The electrode forming apparatus according to claim 33, characterized in that, When the mold conveyor belt (171) is higher than the material conveyor belt in the horizontal direction, the height is selected from 0.5-1mm.

39. The electrode forming apparatus according to claim 33, characterized in that, The fabric feeding device (13) includes a fabric feeding port (131) and a material tank (132), and the material tank (132) is fixedly connected to the fabric feeding port (131).

40. The electrode forming apparatus according to claim 33, characterized in that, The primary stamping device (15) includes a primary punch (151) and a primary stamping base (152). The primary stamping base (152) is fixedly connected to the primary punch (151). The primary punch (151) protrudes from the primary stamping base (152). The shape of the primary punch (151) matches the electrode film mold (172) and is used to perform primary stamping on the material in the electrode film mold (172).

41. The electrode forming apparatus according to claim 40, characterized in that, The electrode film mold (172) includes a primary electrode film grid, which connects the front and back sides of the electrode mold (172) and its width matches the material conveyor belt (11). The primary punch (151) matches the primary electrode film grid, and the size of the primary punch (151) is 0.8mm-1.2mm smaller than the size of the primary electrode film grid.

42. The electrode forming apparatus according to claim 40, characterized in that, The primary punch (151) is divided into primary stamping blocks (1511) by longitudinally and transversely distributed grooves. The electrode film mold (172) includes an electrode tab (1722) and a partition (1726). The electrode tab (1722) and the partition (1726) are crisscrossed to divide the primary electrode film grid into electrode film grids (1721). The electrode film grids (1721) cooperate with the primary stamping blocks (1511), and the size of the primary stamping blocks (1511) is 0.8mm-1.2mm smaller than the size of the electrode film grids (1721).

43. The electrode forming apparatus according to claim 40, characterized in that, The primary stamping base (152) is also provided with a positioning protrusion (153) that cooperates with the electrode film mold (172).

44. The electrode forming apparatus according to claim 33, characterized in that, The electrode mold (172) is also provided with a positioning hole (1724) that cooperates with the positioning protrusion (153) on the first-stage stamping device (15).

45. The electrode forming apparatus according to claim 44, characterized in that, The number of positioning holes (1724) is ≥2.

46. ​​The electrode forming apparatus according to claim 44, characterized in that, The number of positioning holes (1724) is selected from 4 to 8.

47. The electrode forming apparatus according to claim 33, characterized in that, The secondary stamping device (16) includes a secondary punch (161) and a secondary stamping base (162). The secondary stamping base (162) is fixedly connected to the secondary punch (161), and the secondary punch (161) protrudes from the secondary stamping base (162).

48. The electrode forming apparatus according to claim 33, characterized in that, The electrode film mold (172) is also provided with a positioning part (1723), which is located on the left and right sides of the electrode film mold (172).

49. The electrode forming apparatus according to claim 33, characterized in that, The mold conveyor belt (171) is provided with positioning cards (1711). The positioning cards (1711) appear in pairs to form a slot that cooperates with the positioning part (1723) of the electrode film mold (172). The positioning part (1723) is engaged in the slot formed by the positioning card (1711).

50. The electrode forming apparatus according to claim 33, characterized in that, The electrode film mold (172) is also provided with a placement handle (1725), which is respectively located on the left and right sides of the electrode film mold (172), and the number of placement handles (1725) is ≥2.

51. The electrode forming apparatus according to claim 50, characterized in that, The number of the placement handles (1725) is selected from 2-4; The mold placement device (173) includes a placement support arm (1731) and a first support base (1732). The placement support arm (1731) cooperates with the placement handle (1725) of the electrode film mold (172). The first support base (1732) is detachably connected to the placement support arm (1731).

52. The electrode forming apparatus according to claim 33, characterized in that, The mold recycling device (174) includes a recycling clamping arm (1741) and a second support base (1742). The recycling clamping arm (1741) cooperates with the placement handle (1725) of the electrode film mold (172). The second support base (1742) is detachably connected to the recycling clamping arm (1741).

53. The electrode forming apparatus according to claim 33, characterized in that, The current collector unwinding device (21) includes a current collector roll (211), a first roller pair (212), and a second roller pair (213). The current collector roll (211) is used to unwind the current collector, and the second roller pair (213) is used to guide the current collector and the electrode film after being combined by the hot stamping device (22) into the heating demolding device (23).

54. The electrode forming apparatus according to claim 33, characterized in that, The electrode winding device (24) includes an electrode roll (241) and a third roller pair (242). The third roller pair (242) guides the electrode after passing through the heating demolding device (23). The electrode roll (241) winds up the electrode.

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