Electrode powder as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electrode processing and manufacturing. The invention provides electrode powder as well as a preparation method and application thereof, and the preparation method is characterized in that fibrillated powder obtained by a dry electrode technology is sequentially subjected to vibration dispersion and vibration granulation, so that the electrode powder is obtained. Dispersion and secondary granulation are carried out in a vibration mode to form electrode powder with certain flowability, so that when the electrode powder is rolled to form a film, a continuous diaphragm with uniform thickness and density can be prepared in a continuous production mode, the cohesiveness and the tension strength are not influenced, and the electrode powder is uniform in thickness and density. Therefore, the production quality, the production efficiency and the performance of the obtained electrode are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electrode processing and preparation, and relates to an electrode powder and a preparation method and application thereof. Background Art

[0002] With the rapid development of the new energy industry, higher requirements are placed on the processing technology of capacitors, secondary batteries and other devices. In the process of electrode preparation, factors such as raw materials, equipment, process, environment and production control standards will affect the production efficiency and quality of electrode products. It is necessary to accurately control the process and strictly control the standardization of products.

[0003] At present, in the preparation process of electrodes for capacitors and secondary batteries, a wet process is widely used in which a mixed slurry (made using a liquid solvent or dispersant) is coated on a substrate for sheeting; however, the recovery of the liquid will greatly increase energy consumption, and during the drying and recovery process of the liquid phase system, the coating structure will inevitably change and deviate from the target design state. The uncontrollability of this coating structure will also have a serious impact on the performance of the electrode sheet.

[0004] Compared with the wet process, the implementation of dry electrode technology can greatly avoid the energy consumption caused by homogenization and liquid recovery, and is conducive to shortening the processing steps; because dry electrode technology uses a small amount or even basically no liquid, its electrode structure can better meet the requirements of designability and stability.

[0005] Usually, the process route adopted by dry electrode technology is to dry-mix the active main material, conductive agent, fiberizable binder and other additives in one step or in steps, and then store the evenly mixed powder at high temperature to make the binder expand due to heat, causing the dense particles to transform into fluffy lumps, and then under the action of high-speed shear force, the granular binder forms fibers to obtain a fibrillated powder. This powder is then used to continue roller molding to produce dry electrodes.

[0006] However, in the above conventional dry electrode process, the fiberized binder is mixed with the active main material and other powders. Due to the fibrous state of the binder, the mixed powder is very easy to form lumps or flocs during the stirring process, which makes it difficult to meter the feed during the subsequent roller forming and fails to meet the uniformity requirements. It often requires a very large roller pressure to extrude and stretch the flocs or lumps to form a continuous film. It is precisely because of the agglomeration of the lumpy or flocculent mixed powder itself that the continuity and uniformity of the physical properties of the electrode sheet, such as thickness, density and tensile strength, are difficult to guarantee.

[0007] The prior art discloses a method for processing electrode materials and an electrode plate, wherein the method comprises stirring the fiberized material at a low speed of 100 to 500 rpm to break it up, thereby facilitating roller pressing feeding and forming a continuous and uniform film to a certain extent; another prior art discloses a method for preparing a dry electrode plate, wherein the method comprises shearing and granulating the fiberized material at a speed of 400 to 600 rpm at a low speed to form 1 cm particles, thereby facilitating roller pressing feeding and forming a continuous and uniform film to a certain extent.

[0008] However, in the above dry electrode technical solution, since the bonding effect relies on the fiberized binder to connect the component particles, if the binder that has been fiberized is further subjected to the process and procedure of stirring and breaking up, its fiberized structure will be destroyed by the shear force, and the fibers will be further shortened or even cause excessive fiberization, resulting in a serious reduction in the strength of the binder fibers, and thus it is impossible to form effective crosslinks and bonds between the short fibers, which ultimately causes the film layer of the electrode sheet to have a macroscopic strength reduction, thereby affecting the performance of the electrode sheet.

[0009] In view of this, it is necessary to provide a new method for processing powder after dry electrode fiberization and a dry electrode processing method. Summary of the invention

[0010] In view of the problems existing in the prior art, the purpose of the present invention is to provide an electrode powder and a preparation method and use thereof, wherein the preparation method is to obtain an electrode powder by successively performing vibration dispersion and vibration granulation on the fibrillated powder obtained by dry electrode technology. The electrode powder is dispersed and granulated twice by vibration to form an electrode powder with a certain fluidity, so that when rolling to form a film, a continuous film with uniform thickness and density can be produced in a continuous production manner, and the adhesion and tensile strength can be ensured not to be affected, thereby improving the production quality, production efficiency and the performance of the obtained electrode.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a method for preparing an electrode powder, comprising: dry-mixing electrode raw materials to obtain a fibrillated powder; and sequentially vibrating-dispersing and vibrating-granulating the fibrillated powder to obtain an electrode powder.

[0013] The present invention performs dispersion and secondary granulation by means of vibration. Vibration dispersion breaks up flocs and lumps in the fibrillated powder, further optimizing the uniform mixing of the components. Vibration granulation reagglomerates the uniformly dispersed raw materials into uniform secondary particles, providing a basis for the consistency and uniformity of subsequent roller-pressed film formation. While facilitating processing, the electrode sheet film layer is more uniform, and the electrochemical properties such as circulation are improved.

[0014] In short, the combination of vibration dispersion and vibration granulation finally forms an electrode powder with a certain fluidity, so that when it is rolled into a film, it can not only produce a continuous film with uniform thickness and density in a continuous production manner, but also ensure that the adhesion and tensile strength are not affected. At the same time, the obtained electrode powder is easy to feed and meter, thereby improving the production quality, production efficiency and the performance of the obtained electrode.

[0015] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] As a preferred technical solution of the present invention, the electrode raw materials include active main materials, conductive agents and binders; the dry mixing process includes: mixing the electrode raw materials and then dry mixing to obtain mixed powder, and sequentially heat treating and high-speed shearing the mixed powder to fiberize the binder to obtain fibrillated powder.

[0017] Preferably, the binder includes at least one of PTFE (polytetrafluoroethylene), PE (polyethylene), PP (polypropylene) or PEO (polyethylene oxide). For example, typical but non-limiting combination examples include a combination of PTFE and PE, a combination of PTFE and PEO, a combination of PTFE and PP, a combination of PE and PP, a combination of PEO and PP, or a combination of PEO and PE.

[0018] It is understandable that the binder described in the present invention is a fiberizable binder, and thus its fiberization can be achieved through heat treatment and high-speed shearing.

[0019] At the same time, the present invention does not limit the specific material selection and dosage of the active main material and the conductive agent, nor does it limit the dosage of the adhesive. The active main material can be a positive electrode active material or a negative electrode active material, so that the final electrode is a positive electrode or a negative electrode. Furthermore, the electrode raw material of the present invention can also include other auxiliary materials or additives, and those skilled in the art can reasonably adjust and select according to the design objectives and actual needs.

[0020] As a preferred technical solution of the present invention, the dry mixing process includes: first mixing the active main material with the conductive agent and then performing a first dry mixing to obtain a first mixed powder, and then mixing the first mixed powder with the binder and then performing a second dry mixing to obtain a second mixed powder.

[0021] Preferably, the rotation speed of the first dry mixing is 400-600 rpm, for example, 400 rpm, 430 rpm, 450 rpm, 480 rpm, 500 rpm, 530 rpm, 550 rpm, 580 rpm or 600 rpm, and the time is 20-40 min, for example, 20 min, 23 min, 25 min, 28 min, 30 min, 33 min, 35 min, 38 min or 40 min, etc.

[0022] Preferably, after the first mixed powder is cooled and dry-mixed, it is mixed with the binder and subjected to a second dry mixing; the temperature of the cooling and dry mixing is 0-10°C, for example, 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C or 10°C, etc., the rotation speed is 50-150rpm, 50rpm, 60rpm, 70rpm, 80rpm, 90rpm, 100rpm, 110rpm, 120rpm, 130rpm, 140rpm or 150rpm, etc., and the time is 5-15min, for example, 5min, 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min or 15min, etc.

[0023] Preferably, the rotation speed of the second dry mixing is 700-900rpm, for example 700rpm, 730rpm, 750rpm, 780rpm, 800rpm, 830rpm, 850rpm, 880rpm or 900rpm, and the time is 10-60min, for example 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min, etc.

[0024] Preferably, the temperature of the second dry mixing is lower than the softening point of the binder.

[0025] It should be noted that, during the dry mixing process to obtain the mixed powder, the temperature to which the binder is subjected should be lower than its own softening point to avoid fiberization of the binder during dry mixing. Therefore, in order to control the temperature when the binder is added, the present invention preferably cools the first mixed powder for dry mixing to reduce and stabilize the body temperature.

[0026] As a preferred technical solution of the present invention, the temperature of the heat treatment is 90-100°C, for example, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C or 100°C, and the time is 30-180min, for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min or 180min, etc.

[0027] As a preferred technical solution of the present invention, the rotation speed of the high-speed shear is 8000-9000rpm, for example, 8000rpm, 8100rpm, 8200rpm, 8300rpm, 8400rpm, 8500rpm, 8600rpm, 8700rpm, 8800rpm, 8900rpm or 9000rpm, and the time is 5-10min, for example, 5min, 6min, 7min, 8min, 9min or 10min, etc.

[0028] As a preferred technical solution of the present invention, the vibration mode of the vibration dispersion and vibration granulation includes ultrasonic vibration and / or mechanical vibration.

[0029] Preferably, the vibration dispersion and vibration granulation use a vibration screen of 80-150 meshes, such as 80 meshes, 90 meshes, 100 meshes, 110 meshes, 120 meshes, 130 meshes, 140 meshes or 150 meshes.

[0030] Preferably, the number of vibrating screens used in the vibration dispersion and vibration granulation is independently 1 to 3, for example, 1, 2 or 3.

[0031] In the present invention, according to experience, when the number of vibrating screens used for vibration dispersion and vibration granulation is 1 to 3, excellent dispersion and secondary granulation effects can be achieved. Of course, as needed, the number of vibrating screens used for vibration dispersion and vibration granulation can also be more than 3. When at least two vibrating screens are used, the vibrating screens are preferably stacked in the vertical direction so that the material falling from the upper layer of the vibrating screen falls directly into the lower layer of the vibrating screen.

[0032] Preferably, the mesh size of the vibrating screen increases successively along the direction of the material falling in the vibration dispersion.

[0033] Preferably, the mesh size of the vibration screen is the same along the falling direction of the vibration granulation.

[0034] Preferably, the maximum mesh size of the vibrating screen for the vibration granulation is not greater than the maximum mesh size of the vibrating screen for the vibration dispersion.

[0035] In the present invention, the mesh size of the vibration screen for vibration dispersion is gradually reduced to facilitate breaking up the flocculent powder, while the mesh size of the vibration screen for vibration granulation is relatively large to facilitate secondary granulation.

[0036] Preferably, the vibration direction of the vibration dispersion includes vertical vibration, and the vibration direction of the vibration granulation includes horizontal vibration.

[0037] In the present invention, the vertical vibration refers to the up and down vibration perpendicular to the screen surface (along the direction of material falling) when the material is received on the screen surface of the vibrating screen, so that the material "jumps" up and down; the horizontal vibration refers to the "rolling" of the material forward and backward or left and right on the screen surface (perpendicular to the direction of material falling) when the material is received on the screen surface of the vibrating screen.

[0038] In a second aspect, the present invention provides an electrode powder obtained according to the preparation method described in the first aspect.

[0039] As a preferred technical solution of the present invention, the electrode powder is secondary particles.

[0040] Preferably, the electrode powder repose angle of the secondary particles is ≤35°, for example, 35°, 32°, 30°, 28°, 25°, 22°, 20°, 18°, 16°, 13°, 10°, 8°, 5°, 3° or 1°.

[0041] In a third aspect, the present invention provides an electrode comprising the electrode powder described in the second aspect.

[0042] In a fourth aspect, the present invention provides a method for manufacturing the electrode described in the third aspect, wherein the electrode powder described in the third aspect is roll-pressed into a continuous self-supporting electrode film, and then the continuous self-supporting electrode film and a substrate are roll-pressed into an electrode.

[0043] In a fifth aspect, the present invention provides a use of the electrode described in the third aspect, wherein the use includes a secondary battery or a supercapacitor.

[0044] Due to space limitations and to avoid redundancy, the present invention does not list all point values ​​within the above numerical range one by one, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0045] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0046] The present invention obtains fibrillated powder by dry method, and performs vibration dispersion and vibration granulation in sequence to obtain electrode powder. Dispersion and secondary granulation are performed by vibration to form electrode powder with certain fluidity, so that when rolling film, continuous film with uniform thickness and density can be obtained in a continuous production mode, and adhesion and tension strength can be ensured not to be affected. At the same time, the obtained electrode powder is convenient for feeding and metering, thereby improving production quality, production efficiency and performance of the obtained electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic flow chart of the method for preparing the electrode powder of Example 1;

[0048] Figure 2 It is a schematic flow chart of a method for manufacturing an electrode containing the electrode powder of the present invention;

[0049] Figure 3 Schematic diagram of the ultrasonic vibrating screen in Example 1. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0051] It should be clear to those skilled in the art that the embodiments are only intended to help understand the present invention and should not be considered as specific limitations of the present invention.

[0052] Example 1

[0053] This embodiment provides a method for preparing electrode powder, such as Figure 1 As shown, the preparation method comprises:

[0054] (1) Weighing active substrate NCM811, conductive agent carbon black and binder PTFE powder in a mass ratio of 96.5:2:1.5; adding the active substrate and the conductive agent into a stirrer, performing a first dry mixing at 500 rpm for 30 min at room temperature to obtain a first mixed powder; using low-temperature cooling water to control the temperature, cooling the obtained first mixed powder at 100 rpm for 10 min at below 10° C. to obtain a cooled mixed powder; adding a binder into the stirrer, mixing the cooled mixed powder with the binder, performing a second dry mixing at 800 rpm for 35 min, controlling the temperature of the second dry mixing to be less than the softening point of the binder to avoid premature fiberization of the binder, and obtaining a second mixed powder;

[0055] (2) heat treating the obtained second mixed powder in an oven at 95° C. for 110 min, and then subjecting the mixed powder to high-speed shearing at a stirring speed of 8500 rpm for 8 min to fiberize the binder to obtain a fibrillated powder;

[0056] (3) Prepare an ultrasonic vibrating screen, such as Figure 3 As shown, four ultrasonic vibrating screens are stacked from top to bottom, with mesh sizes of 80 mesh, 150 mesh, 150 mesh and 150 mesh, respectively. The screen surface is horizontal, and the upper and lower adjacent vibrating screens are connected by elastic connectors; wherein the first two ultrasonic vibrating screens vibrate up and down in the vertical direction, and the last two ultrasonic vibrating screens vibrate back and forth in the horizontal direction.

[0057] The obtained fibrillated powder is placed in the top ultrasonic vibration screen, so that during the process of the fibrillated powder falling, vibration dispersion is carried out and completed in the first two ultrasonic vibration screens, and vibration granulation is carried out and completed in the last two ultrasonic vibration screens, and finally the electrode powder of secondary particles under the screen is obtained, and the repose angle of the electrode powder is 15.4°.

[0058] Example 2

[0059] This embodiment provides a method for preparing an electrode powder, the preparation method comprising:

[0060] (1) Weigh active substrate graphite, conductive agent SP and binder PTFE powder in a mass ratio of 97%:1.5%:1.5%; add the active substrate and the conductive agent into a stirrer, and perform a first dry mixing at 400 rpm for 40 minutes at room temperature to obtain a first mixed powder; use low-temperature cooling water to control the temperature, and cool the obtained first mixed powder at 50 rpm for 15 minutes at a temperature below 10° C. to obtain a cooled mixed powder; add a binder into the stirrer, mix the cooled mixed powder with the binder, and perform a second dry mixing at 700 rpm for 45 minutes, controlling the temperature of the second dry mixing to be less than the softening point of the binder to avoid premature fiberization of the binder, to obtain a second mixed powder;

[0061] (2) heat treating the obtained second mixed powder in an oven at 90° C. for 180 min, and then subjecting the mixed powder to high-speed shearing at a stirring speed of 8000 rpm for 10 min to fiberize the binder to obtain a fibrillated powder;

[0062] (3) preparing ultrasonic vibrating screens, wherein three ultrasonic vibrating screens are stacked from top to bottom, with mesh sizes of 80 mesh, 150 mesh, and 150 mesh, respectively, and the screen surface is horizontal, wherein the first two ultrasonic vibrating screens vibrate up and down in the vertical direction, and the third ultrasonic vibrating screen vibrates back and forth in the horizontal direction,

[0063] The obtained fibrillated powder is placed in the top ultrasonic vibration screen, so that during the process of the fibrillated powder falling, vibration dispersion is carried out and completed in the first two ultrasonic vibration screens, and vibration granulation is carried out and completed in the third ultrasonic vibration screen, and finally the electrode powder under the screen is obtained, and the repose angle of the electrode powder is 15.4°.

[0064] Example 3

[0065] This embodiment provides a method for preparing an electrode powder, the preparation method comprising:

[0066] (1) Weighing active substrate MgTiO3, activated carbon and binder PTFE powder in a mass ratio of 95%:3%:2%; adding the active substrate and the conductive agent into a stirrer, performing a first dry mixing at 600 rpm for 20 min at room temperature to obtain a first mixed powder; using low-temperature cooling water to control the temperature, cooling the obtained first mixed powder at 150 rpm for 5 min at a temperature below 10°C to obtain a cooled mixed powder; adding a binder into the stirrer, mixing the cooled mixed powder with the binder, performing a second dry mixing at 900 rpm for 25 min, controlling the temperature of the second dry mixing to be less than the softening point of the binder to avoid premature fiberization of the binder, and obtaining a second mixed powder;

[0067] (2) heat treating the obtained second mixed powder in an oven at 100° C. for 80 min, and then subjecting the mixed powder to high-speed shearing at a stirring speed of 8000 rpm for 5 min to fiberize the binder and obtain a fibrillated powder;

[0068] (3) preparing an ultrasonic vibrating screen, wherein five ultrasonic vibrating screens are stacked from top to bottom, and the mesh sizes are 80 mesh, 120 mesh, 150 mesh, 150 mesh and 150 mesh, respectively, and the screen surface is horizontal, wherein the first three ultrasonic vibrating screens vibrate up and down in the vertical direction, and the last two ultrasonic vibrating screens vibrate back and forth in the horizontal direction,

[0069] The obtained fibrillated powder is placed in the top ultrasonic vibration screen, so that during the process of the fibrillated powder falling, vibration dispersion is carried out and completed in the first three ultrasonic vibration screens, and vibration granulation is carried out and completed in the last two ultrasonic vibration screens, and finally the electrode powder under the screen is obtained, and the repose angle of the electrode powder is 15.7°.

[0070] Example 4

[0071] This embodiment provides a method for preparing an electrode powder, wherein in step (1), cooling and dry mixing are not performed, and the first mixed powder is directly subjected to second dry mixing, and the angle of repose of the obtained electrode powder is 23.4°. Except for the above, other conditions are exactly the same as those in Example 1.

[0072] Example 5

[0073] This embodiment provides a method for preparing an electrode powder, wherein the preparation method does not perform heat treatment in step (2), but directly performs high-speed shearing, and the repose angle of the electrode powder is 15.1°. Except for the above, other conditions are exactly the same as those in Example 1.

[0074] Example 6

[0075] This embodiment provides a method for preparing an electrode powder, wherein in step (2), the high-speed shearing time is adjusted from 8 min to 15 min, and the repose angle of the electrode powder is 11.3°. Except for the above, other conditions are exactly the same as those in Example 1.

[0076] Example 7

[0077] This embodiment provides a method for preparing an electrode powder, wherein a mechanical vibrating screen is used in place of the ultrasonic vibrating screen in step (3), and the angle of repose of the electrode powder is 14.6°. Except for the above, other conditions are exactly the same as those in Example 1.

[0078] Example 8

[0079] This embodiment provides a method for preparing an electrode powder, wherein in step (3), the number of ultrasonic vibration screens is adjusted from 4 to 2, and the mesh sizes are 150 mesh and 150 mesh, respectively, wherein the first ultrasonic vibration screen vibrates up and down in the vertical direction, and the second ultrasonic vibration screen vibrates back and forth in the horizontal direction, and vibration dispersion is performed and completed in the first ultrasonic vibration screen, and vibration granulation is performed and completed in the second ultrasonic vibration screen, and finally the electrode powder under the screen is obtained, and the repose angle of the electrode powder is 28.2°. Except for the above, other conditions are exactly the same as those in Example 1.

[0080] Example 9

[0081] This embodiment provides a method for preparing an electrode powder, wherein in step (3), the number of ultrasonic vibration screens is adjusted from 4 to 6, and the mesh sizes are 80 mesh, 120 mesh, 150 mesh, 150 mesh, 150 mesh and 150 mesh, respectively, wherein the first three ultrasonic vibration screens vibrate up and down in the vertical direction, and the last three ultrasonic vibration screens vibrate back and forth in the horizontal direction, and vibration dispersion is performed and completed in the first three ultrasonic vibration screens, and vibration granulation is performed and completed in the last three ultrasonic vibration screens, and finally the electrode powder under the screen is obtained, and the repose angle of the electrode powder is 11.4°. Except for the above, other conditions are exactly the same as those in Example 1.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing an electrode powder, wherein the preparation method does not perform step (3) and directly uses the fibrillated powder obtained in step (2). The electrode powder does not have fluidity and the angle of repose cannot be measured. Except for the above, the other conditions are exactly the same as those in Example 1.

[0084] Comparative Example 2

[0085] This comparative example provides a method for preparing an electrode powder, wherein the preparation method does not perform step (3) and directly uses the fibrillated powder obtained in step (2), and the repose angle of the electrode powder is 38.4°. Except for the above, other conditions are exactly the same as those in Example 2.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing an electrode powder, wherein the preparation method does not perform step (3) and directly uses the fibrillated powder obtained in step (2), and the repose angle of the electrode powder is 42.1°. Except for the above, the other conditions are exactly the same as those in Example 3.

[0088] Comparative Example 4

[0089] This comparative example provides a method for preparing an electrode powder. In step (3), only vibration dispersion is performed without vibration granulation, and the sample obtained by vibration dispersion is directly used. Except for the above, other conditions are exactly the same as those in Example 1. The angle of repose of the electrode powder is 62.7°.

[0090] Comparative Example 5

[0091] This comparative example provides a method for preparing an electrode powder. In the preparation method, in step (3), the vibration dispersion and vibration granulation are not performed, but the fibrillated powder obtained in step (2) is stirred at a low speed of 300 rpm for dispersion. Except for the above, other conditions are exactly the same as those in Example 1. The electrode powder does not have fluidity and the angle of repose cannot be measured.

[0092] Application Example 1

[0093] The electrode powders obtained in Examples 1-9 and Comparative Examples 1-5 were used to make electrodes. Figure 2 As shown, the manufacturing method of the electrode includes placing the electrode powder in a dry powder metering feeding system to accurately measure the feeding amount, preliminarily pre-pressing the electrode powder into a film by rolling, and then performing multi-stage thinning by multiple rolling to form a uniform and continuous self-supporting electrode film, and then compounding the self-supporting electrode film with a substrate by rolling to form an electrode.

[0094] The obtained electrode was subjected to membrane tension strength and surface density fluctuation tests. The membrane strength was tested by a universal tensile testing machine. Circular samples with a diameter of 5 cm were cut along the width and length directions. The sample surface density was calculated, and the difference between the maximum and minimum values ​​was taken to calculate the surface density fluctuation range. The results are recorded in Table 1.

[0095] Table 1

[0096] Electrode powder Diaphragm tension strength N / m Density fluctuation in width direction / 80cm Length direction surface density fluctuation / 10m Example 1 25 0.1％ 0.020％ Example 2 6 0.08％ 0.015％ Example 3 22 0.11％ 0.018％ Example 4 7 1.2％ 0.032％ Example 5 12 0.2％ 0.025％ Example 6 18 0.1％ 0.018％ Example 7 23 0.1％ 0.022％ Example 8 8 0.3％ 3％ Example 9 24 0.11％ 0.019％ Comparative Example 1 5 2.2％ 2.300％ Comparative Example 2 0.5 1.3％ 1.1％ Comparative Example 3 4 2.4％ 1.8％ Comparative Example 4 8 0.5％ 2.4％ Comparative Example 5 12 4.2％ 1.200％

[0097] It can be seen from Table 1 that:

[0098] In Example 2, due to the properties of the graphite negative electrode itself, its tensile strength is lower than that of Example 1; and during roll forming, due to the self-lubricating property of the graphite itself, its surface density fluctuates less;

[0099] The physical properties of the main material of Example 3 are similar to those of the main material of Example 1, so the properties of the diaphragms are similar;

[0100] In Example 4, there is no cooling water, which causes the binder to be fiberized during mixing and stirring. When fiberized again at a high speed, the binder is over-fiberized, the fiber length is shortened, and the strength of the formed membrane is low;

[0101] In Example 5, there is no heat treatment process, the binder is not fully fiberized, and the strength of the formed membrane is low;

[0102] In Example 6, the high-speed stirring time of the binder was too long, resulting in excessive fiberization, which caused the fibers to be broken, and the strength of the formed membrane was low;

[0103] In Example 7, mechanical vibration was used, and the dispersion and granulation effects were similar to those of ultrasonic vibration, but the dispersion and granulation effects were inferior to those of ultrasonic vibration. The secondary structure in the particles could not be dispersed, and the homogenization was insufficient, so the tension strength of the membrane was slightly reduced.

[0104] In Example 8, the dispersion and granulation effects were poor, which resulted in uneven distribution of materials when the membrane was rolled, resulting in poor consistency of surface density and low strength;

[0105] In Example 9, more layers of screens were used, and the dispersion and granulation effects were significant, but there was no significant improvement in the performance of the membrane;

[0106] Therefore, reasonable stirring, dispersing and granulation methods can produce electrode membranes with high tensile strength and good membrane consistency.

[0107] In summary, through the preparation method described in the present invention, the floc structure of the fibrillated powder is broken up and dispersed after vibration dispersion, and then after vibration granulation, due to the properties of the fiber itself, when vibrating left and right, it agglomerates into small particles and passes through the screen to form a uniform spherical secondary particle electrode powder. The electrode powder can then be used to prepare a continuous, uniform, and uniformly thick self-supporting electrode film, and further compounded to form an electrode sheet.

[0108] Application Example 2

[0109] The electrodes obtained from Examples 1, 2, 4-9 and Comparative Examples 1, 2, 4 and 5 in Application Example 1 are used as positive pole pieces or negative pole pieces to assemble into a battery. The battery assembling method includes cutting the above-mentioned positive pole pieces into original sheets with a diameter of 12 mm, and the counter electrode is the negative pole piece obtained from Example 2, and assembling them into a CR2032 button battery.

[0110] The obtained battery was tested and the results are recorded in Table 2.

[0111] Table 2

[0112]

[0113]

[0114] It can be seen from Table 2 that:

[0115] The positive electrode prepared by Example 1 and the negative electrode prepared by Example 2 have relatively high first efficiency and cycle retention rate. The uniformity of the pole piece (macroscopically) is positively correlated with the effect of granulation, so the material is required to be evenly dispersed, and the fluctuations in tension and length can only represent the difficulty of processing and manufacturing and the consistency of the battery cell; combined with the results of Example 8 in Table 1, although the ultrasonic vibration in Example 8 cannot guarantee the granulation processing effect, it can guarantee the uniformity of the material, so the cycle capacity of the battery cell itself will not deteriorate too much. In Comparative Example 4, since cooling water is not used, the structure of the material itself will be damaged, thereby deteriorating the retention rate.

[0116] Application Example 3

[0117] The electrodes obtained from Example 3 and Comparative Example 3 in Application Example 1 are assembled into a supercapacitor. The supercapacitor assembly method includes cutting the electrode plates into original sheets with a diameter of 12 mm, and assembling them into CR2032 button batteries with symmetrical electrodes.

[0118] The obtained supercapacitor was tested and the results are recorded in Table 3.

[0119] Table 3

[0120] electrode 5A / 1A capacity retention rate Example 3 99 Comparative Example 3 87

[0121] It can be seen from Table 3 that:

[0122] The capacitor assembled by Example 3 has better rate performance.

[0123] As can be seen from the above, the present invention obtains fibrillated powder by dry method, and then performs vibration dispersion and vibration granulation in sequence to obtain electrode powder. Dispersion and secondary granulation are performed by vibration to form electrode powder with certain fluidity, so that when rolling film, continuous film with uniform thickness and density can be obtained in a continuous production manner, and adhesion and tension strength can be ensured not to be affected. At the same time, the obtained electrode powder is convenient for feeding and metering, thereby improving production quality, production efficiency and performance of the obtained electrode.

[0124] The present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0125] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0126] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0127] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing an electrode powder, characterized in that: include: Dry-mixing electrode raw materials to obtain fibrillated powder; The fibrillated powder is subjected to vibration dispersion and vibration granulation in sequence to obtain electrode powder.

2. The method for preparing electrode powder according to claim 1, characterized in that: The electrode raw materials include active main materials, conductive agents and binders; the dry mixing process includes: mixing the electrode raw materials and then dry mixing to obtain mixed powder, and sequentially heat treating and high-speed shearing the mixed powder to fibrillate the binder to obtain fibrillated powder; Preferably, the binder includes at least one of polytetrafluoroethylene, polyethylene, polypropylene or polyethylene oxide.

3. The method for preparing electrode powder according to claim 2, characterized in that: The dry mixing process includes: firstly mixing the active main material with the conductive agent and then performing a first dry mixing to obtain a first mixed powder, and then mixing the first mixed powder with the binder and then performing a second dry mixing to obtain a second mixed powder; Preferably, the first dry mixing has a rotation speed of 400 to 600 rpm and a time of 20 to 40 min; Preferably, after the first mixed powder is cooled and dry-mixed, it is mixed with the binder and subjected to a second dry-mixing; the temperature of the cooling and dry-mixing is 0 to 10° C., the rotation speed is 50 to 150 rpm, and the time is 5 to 15 minutes; Preferably, the second dry mixing has a rotation speed of 700 to 900 rpm and a time of 10 to 60 min; Preferably, the temperature of the second dry mixing is lower than the softening point of the binder.

4. The method for preparing electrode powder according to claim 2 or 3, characterized in that: The heat treatment temperature is 90-100°C and the time is 30-180min; Preferably, the high-speed shearing speed is 8000-9000 rpm and the time is 5-10 min.

5. The method for preparing the electrode powder according to any one of claims 2 to 4, characterized in that: The vibration mode of the vibration dispersion and vibration granulation includes ultrasonic vibration and / or mechanical vibration; Preferably, the vibration dispersion and vibration granulation use a vibration screen of 80 to 150 meshes; Preferably, the number of vibrating screens used in the vibration dispersion and vibration granulation is independently 1 to 3; Preferably, along the falling direction of the vibration dispersion, the mesh size of the vibration screen increases successively; Preferably, along the falling direction of the vibration granulation, the mesh size of the vibration screen is the same; Preferably, the maximum mesh size of the vibrating screen for the vibration granulation is not greater than the maximum mesh size of the vibrating screen for the vibration dispersion; Preferably, the vibration direction of the vibration dispersion includes vertical vibration, and the vibration direction of the vibration granulation includes horizontal vibration.

6. An electrode powder, characterized in that: Obtained according to the preparation method according to any one of claims 1 to 5.

7. The electrode powder according to claim 6, characterized in that: The electrode powder is a secondary particle; Preferably, the electrode powder repose angle of the secondary particles is ≤35°.

8. An electrode, characterized in that: Contains the electrode powder according to claim 6 or 7.

9. A method for manufacturing an electrode according to claim 8, characterized in that: The electrode powder material according to claim 6 or 7 is roll-pressed into an electrode film, and then the electrode film and a substrate are roll-pressed into an electrode.

10. Use of the electrode according to claim 8, characterized in that: The uses include secondary batteries or supercapacitors.

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