CN110071288B - Negative electrode slurry and preparation method and application thereof - Google Patents
Negative electrode slurry and preparation method and application thereof Download PDFInfo
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- CN110071288B CN110071288B CN201910264882.5A CN201910264882A CN110071288B CN 110071288 B CN110071288 B CN 110071288B CN 201910264882 A CN201910264882 A CN 201910264882A CN 110071288 B CN110071288 B CN 110071288B
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- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
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Abstract
The invention discloses a negative electrode slurry and a preparation method and application thereof, wherein the method comprises the following steps: adding a negative electrode active material, a conductive agent and a thickening agent into a three-axis planetary mixer for mixing and stirring to obtain a first mixed material; adding an additive into the first mixed material and stirring to obtain a second mixed material; adding a solvent into the second mixed material and stirring under a vacuum condition to obtain a first mixed slurry with the solid content of 80-90 wt%; adding a solvent into the first mixed slurry and continuously stirring under a vacuum condition to obtain a second mixed slurry with the solid content of 60-72 wt%; adding a binder and a solvent into the second mixed slurry, and continuously stirring under a vacuum condition to obtain a third mixed slurry with the solid content of 53-58 wt%; and adding a solvent into the third mixed slurry, and continuously stirring under a vacuum condition to obtain the negative electrode slurry with the viscosity value of 3000-8000 mPa & s. The method can effectively solve the problem of infiltration of the negative active material and the solvent at the initial stirring stage, shorten the stirring time of the slurry and improve the viscosity consistency of the slurry.
Description
Technical Field
The invention belongs to the field of lithium ion batteries, and particularly relates to negative electrode slurry and a preparation method and application thereof.
Background
In order to meet the requirements of the domestic power lithium battery market, various large lithium battery manufacturers continuously optimize the lithium battery process. The homogenizing and stirring process is an important process for manufacturing the lithium battery in the lithium battery industry, occupies 30% of the process, plays a decisive role, and determines the quality of the slurry stirring in the later coating and the final performance of the lithium battery.
At present, the negative (positive) electrode of the mainstream enterprise of the lithium battery at home and abroad mainly uses copper foil as a current collector, and a graphite system as an active substance. The coating process, another key manufacturing process of the lithium ion battery, is a subject of active improvement and development of various large lithium power plant merchants at present. The content includes the appearance of the electrode plate, coating uniformity, dimensional accuracy, and the ratio of merit, etc., wherein the appearance and ratio of merit of the negative electrode coating are one of the most challenging issues. Because the cathode slurry uses an aqueous system, the graphite has certain hydrophobicity. For the cathode slurry adopting deionized water as a solvent, the infiltration of graphite by water has certain difficulty, and particularly for some graphite with small particle size and large specific surface area, various poor appearances such as particle scratches, bubbles, black spots, pockmarks and the like can occur during coating, and the product goodness is seriously influenced. Therefore, the quality of the negative electrode slurry directly determines the quality of the coated product, and thus, the stirring process of the negative electrode slurry becomes more and more important, and becomes the leading research direction of various large lithium battery manufacturers.
In order to solve the problems of poor appearance and good rate of the anode coating, at present, two main solutions are available in the stirring process: the first is to improve the dispersibility of the cathode slurry, for example, the high-speed dispersion and kneading stirring and other batching processes are adopted, the high-speed dispersion has long stirring time and high energy consumption and has certain destructive effect on organic polymers such as a stabilizer, a binder and the like in a formula, so that the stability of the slurry and the binding power of a pole piece are influenced; for a double-planet mixer commonly used at present, the kneading stirring has requirements on the solid content of the kneading because the torque force of the revolution paddle is not strong enough, and if the solid content is too high, the viscous resistance is too large, so that the revolution paddle can not rotate. The second is to change the composition of the negative electrode slurry, and the components which can be added often remain in the pole piece, so that the performance of the battery cell is affected, and meanwhile, the improvement effect is unstable and needs to be repeated.
Therefore, the existing preparation method of the anode slurry needs to be further improved.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention aims to provide a negative electrode slurry and a preparation method and application thereof. The method can effectively solve the problem of infiltration of the negative active material and the solvent in the initial stirring stage, and can also obviously shorten the stirring time of the slurry and improve the viscosity consistency of the slurry.
In one aspect of the present invention, the present invention provides a method of preparing a negative electrode slurry, the method including, according to an embodiment of the present invention:
(1) adding a negative electrode active material, a conductive agent and a thickening agent into a three-axis planetary mixer for mixing and stirring so as to obtain a first mixed material;
(2) adding an additive into the first mixed material and stirring to obtain a second mixed material;
(3) adding a solvent into the second mixed material and stirring under a vacuum condition so as to obtain a first mixed slurry with the solid content of 80-90 wt%;
(4) adding the solvent into the first mixed slurry and continuously stirring under a vacuum condition so as to obtain a second mixed slurry with the solid content of 60-72 wt%;
(5) adding a binder and the solvent into the second mixed slurry and continuously stirring under a vacuum condition so as to obtain a third mixed slurry with the solid content of 53-58 wt%;
(6) and adding the solvent into the third mixed slurry and continuously stirring under a vacuum condition so as to obtain the negative electrode slurry with the viscosity value of 3000-8000 mPa & s.
According to the method for preparing the cathode slurry, disclosed by the embodiment of the invention, the cathode active material, the conductive agent and the thickening agent are supplied to the three-axis planetary mixer for mixing and stirring, so that the macro mixing among the powder is realized, and the opening of powder particle agglomeration and the infiltration of the powder particle surface in subsequent high-viscosity stirring are facilitated. Simultaneously, the mixing and stirring are carried out in a three-shaft planetary stirrer, and compared with the traditional double-planetary stirrer without a high-speed dispersion plate, the high-speed dispersion plate is prevented from high-speed shearing damage to the molecular structure of the thickening agent in the slurry and damage to the subsequent adhesive, and the stability of the slurry and the adhesive force of a pole piece are favorably improved. Furthermore, the revolution paddle of the three-axis planetary mixer has stronger torque force than the double-planet revolution paddle, so that the surface infiltration of powder particles and the shearing kneading action of slurry are facilitated, the stirring time is further shortened, and high-viscosity kneading stirring with higher solid content can be performed. The additive is beneficial to improving the wettability of the surface of the powder particles, and is further beneficial to the dispersion of the powder particles after the solvent is subsequently added. The solid content of the first mixed slurry is controlled to be 80 wt% -90 wt%, so that the shearing friction effect among powder particles is improved, and the wetting of the particle surfaces is further promoted. The solid content of the second mixed slurry is controlled to be 60 wt% -72 wt%, and the high-strength shearing kneading effect of the triaxial planetary mixer is combined, so that the kneading shearing effect among the wetting powder particles is very strong, agglomerated particles are favorably dispersed, and meanwhile, the thickening agent particles start to be stripped and dissolved layer by layer through the strong kneading shearing effect. Controlling the solid content of the third mixed slurry to be 53-58 wt%, under the high-strength shearing kneading action of a three-axis planetary mixer, facilitating the binder and particles to be better dispersed in the solvent, promoting the thickener to be completely dissolved to obtain uniformly dispersed and stable slurry, and then adjusting the viscosity to obtain the negative electrode slurry with the viscosity value of 3000-8000 mPa & s. Therefore, the method can effectively solve the problem of infiltration of the negative active material and the solvent in the initial stirring stage, obviously shorten the stirring time of the slurry and improve the viscosity consistency of the slurry.
In addition, the method of preparing anode slurry according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the present invention, in the step (1), the revolution speed of the three-axis planetary mixer is 5-10 rpm, the rotation speed is 15-30 rpm, and the mixing time is 5-10 min. This can further improve the efficiency of macro mixing between the powders.
In some embodiments of the present invention, in the step (1), the mass ratio of the negative electrode active material to the conductive agent to the thickener is (92 to 98): (0.5-4): (0.5-2). This can further improve the quality of the negative electrode slurry.
In some embodiments of the present invention, in the step (1), the negative active material is at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, and soft carbon. This can further improve the quality of the negative electrode slurry.
In some embodiments of the present invention, in the step (1), the conductive agent is at least one selected from the group consisting of super conductive carbon, carbon nanotube, graphene and conductive graphite. This can further improve the quality of the negative electrode slurry.
In some embodiments of the invention, in step (1), the thickener is at least one selected from CMC powder, CMC solution. This can further improve the quality of the negative electrode slurry.
In some embodiments of the invention, in the step (2), the revolution speed of the three-axis planetary stirrer is 5-15 rpm, the rotation speed is 15-45 rpm, the stirring time is 10-20 min, and the stirring temperature is 0-40 ℃. Thereby, the mixing effect of the additive and the first mixed material can be further improved.
In some embodiments of the invention, in step (2), the additive is at least one selected from the group consisting of acetone, ethanol, 1, 3-butanediol, NMP. This can further improve the wettability of the powder particle surface.
In some embodiments of the invention, in the step (2), the mass ratio of the additive to the first mixed material is (0.1-5): 100. this can further improve the wettability of the powder particle surface.
In some embodiments of the invention, in the step (3), the revolution speed of the three-axis planetary stirrer is 5-20 rpm, the rotation speed is 15-60 rpm, the stirring time is 10-15 min, and the stirring temperature is 55-70 ℃. This can further improve the shearing friction effect between the powder particles.
In some embodiments of the invention, in step (3), the solvent is at least one of deionized water, NMP. The quality of the anode slurry can be further improved.
In some embodiments of the invention, in the step (4), the revolution speed of the three-axis planetary stirrer is 15-25 rpm, the rotation speed is 45-75 rpm, the stirring time is 40-65 min, and the stirring temperature is 55-70 ℃. This further promotes dispersion of the agglomerate and exfoliation and dissolution of the thickener.
In some embodiments of the invention, in the step (5), the revolution speed of the three-axis planetary stirrer is 5-20 rpm, the rotation speed is 15-60 rpm, the stirring time is 25-35 min, and the stirring temperature is 20-35 ℃. This further promotes dispersion of the binder and the particles in the solvent.
In some embodiments of the present invention, in step (5), the binder is at least one selected from SBR, LA132, LA 133. This can further improve the quality of the negative electrode slurry.
In some embodiments of the invention, in the step (5), the mass ratio of the binder to the first mixed material is (1-5): 100. this can further improve the quality of the negative electrode slurry.
In some embodiments of the invention, in the step (6), the revolution speed of the three-axis planetary stirrer is 5-15 rpm, the rotation speed is 15-45 rpm, the stirring time is 25-35 min, and the stirring temperature is 20-35 ℃. Thereby, the viscosity regulation rate is improved.
In some embodiments of the present invention, in the step (3), the step (4), the step (5), and the step (6), the vacuum degree of the vacuum condition is-90 to-30 kPa, respectively and independently. This can further improve the quality of the negative electrode slurry.
In still another aspect of the present invention, the present invention provides a negative electrode slurry, which is prepared by the above method for preparing a negative electrode slurry according to an embodiment of the present invention. Therefore, the negative electrode slurry has the advantages that the component particles are uniformly dispersed, the viscosity consistency and the stability are higher, and the coating appearance and the binding power of the slurry are improved.
In another aspect of the present invention, the present invention provides a lithium ion battery, according to an embodiment of the present invention, a negative electrode of the lithium ion battery is prepared by using the above negative electrode slurry. Therefore, the binding power of the negative electrode slurry and the current collector in the negative electrode is strong, the negative electrode has good charge and discharge performance due to the fact that the particles of all components in the negative electrode slurry are uniformly dispersed, the performance of the lithium ion battery can be obviously improved, and meanwhile, the cost of the lithium ion battery can be further reduced due to the fact that the production cost of the negative electrode slurry is low.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic flow diagram of a method of preparing an anode slurry according to one embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In one aspect of the present invention, the present invention provides a method of preparing an anode slurry, according to an embodiment of the present invention, with reference to fig. 1, the method including:
s100: adding the negative active material, the conductive agent and the thickening agent into a three-shaft planetary mixer for mixing and stirring
In the step, a negative electrode active material, a conductive agent and a thickening agent are added into a three-axis planetary mixer for mixing and stirring so as to obtain a first mixed material. The inventor finds that macro mixing among the powder is realized by supplying the negative electrode active material, the conductive agent and the thickening agent to a three-shaft planetary mixer for mixing and stirring, and the macro mixing is favorable for opening agglomeration of powder particles and wetting the surfaces of the powder particles in subsequent high-viscosity stirring. Simultaneously, the mixing and stirring are carried out in a three-shaft planetary stirrer, and compared with the traditional double-planetary stirrer without a high-speed dispersion plate, the high-speed dispersion plate is prevented from high-speed shearing damage to the molecular structure of the thickening agent in the slurry and damage to the subsequent adhesive, and the stability of the slurry and the adhesive force of a pole piece are favorably improved. Furthermore, the revolution paddle of the three-axis planetary mixer has stronger torque force than the double-planet revolution paddle, so that the surface infiltration of powder particles and the shearing kneading action of slurry are facilitated, the stirring time is further shortened, and high-viscosity kneading stirring with higher solid content can be performed.
According to an embodiment of the present invention, the revolution speed of the three-axis planetary mixer may be 5 to 10rpm, the rotation speed may be 15 to 30rpm, and the mixing time may be 5 to 10 min. Specifically, the revolution speed of the three-shaft planetary stirrer can be 5rpm, 6rpm, 7rpm, 8rpm, 9rpm and 10 rpm; the rotation speed can be 15rpm, 17rpm, 20rpm, 22rpm, 25rpm, 28rpm and 30 rpm; the time can be 5min, 6min, 7min, 8min, 9min, 10 min. The inventor finds that the stirring speed and time in the stirring process can be obviously reduced and the preparation efficiency of the negative electrode slurry can be improved by adopting a three-shaft planetary stirrer with high shearing action. If the revolution speed and/or the rotation speed of the three-axis planetary stirrer are/is too high, the dust of the powder is very high, the powder with light density is distributed at the upper part, and the powder with heavy density is distributed at the lower part, so that the macroscopic uniform mixing among the powder is not facilitated; if the revolution and/or rotation speed of the three-axis planetary stirrer is too low, the macro blending needs too long time. It should be noted that the revolution speed and the rotation speed of the three-axis planetary mixer described herein refer to the revolution speed and the rotation speed of the mixing paddles in the three-axis planetary mixer, respectively.
According to still another embodiment of the present invention, the mass ratio of the negative electrode active material to the conductive agent and the thickener is not particularly limited, and may be selected by those skilled in the art according to actual needs, and may be, for example, (92 to 98): (0.5-4): (0.5-2). Further, for example, it may be (92/93/94/95/96/97/98): (0.5/1/1.5/2/2.5/3/3.5/4): (0.5/1.0/1.5/2.0). It should be noted that the specific contents of the components of the negative active material, the conductive agent and the thickener can be determined according to manufacturability such as balanced slurry stability, rheological property, pole piece compaction, binding power and the like and electrical property of a subsequently prepared battery. Specifically, the negative active material may be at least one selected from artificial graphite, natural graphite, hard carbon, and soft carbon, the conductive agent may be at least one selected from super conductive carbon, carbon nanotubes, graphene, and conductive graphite, and the thickener may be at least one selected from CMC powder and CMC solution. The inventor finds that the capacity, the service cycle life and the price of the negative electrode active material are all excellent; the conductive agent has excellent conductivity, no other side effect on the electrical property of the battery and lower use cost; the thickening agent has obvious thickening effect in a solvent, has excellent effect on improving the stability of slurry, and has small side effect on the electrical property of the battery when the content of the thickening agent is in the range.
S200: adding the additive into the first mixed material and stirring
In this step, an additive is added to the first mixed material and stirred to obtain a second mixed material. The inventors found that the additive is beneficial to improving the wettability of the surface of the powder particles, and is further beneficial to dispersing the powder particles after a solvent is added subsequently. Specifically, the additive may be at least one selected from acetone, ethanol, 1, 3-butanediol and NMP, and the mass ratio of the additive to the first mixed material may be (0.1-5): 100, for example, can be (0.1/0.5/1.0/1.5/2.0/2.5/3.0/3.5/4.0/4.5/5.0): 100. the inventor finds that the contact angles of the additives acetone, ethanol, 1, 3-butanediol and NMP with the negative active material are small, the additives are easy to infiltrate with the negative active material, and the additives are easy to volatilize and volatilize out in the subsequent coating process, do not remain on a pole piece and have no influence on the electrical property of the battery.
According to an embodiment of the invention, the revolution speed of the three-axis planetary stirrer can be 5-15 rpm, the rotation speed can be 15-45 rpm, the stirring time can be 10-20 min, and the stirring temperature can be 0-40 ℃. Specifically, the revolution speed of the three-shaft planetary stirrer can be 5rpm, 7rpm, 9rpm, 11rpm, 13rpm and 15 rpm; the rotation speed can be 15rpm, 20rpm, 25rpm, 30rpm, 35rpm, 40rpm and 45 rpm; the time can be 10min, 12min, 14min, 16min, 18min, 20 min; the temperature can be 0 deg.C, 5 deg.C, 10 deg.C, 15 deg.C, 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C. The stirring temperature can be controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer. In the above temperature range, the diffusion movement of the molecules of the components in the powder is intensified, thereby improving the mixing of the powder particles and the additive. The inventor finds that if the revolution and rotation speeds of the three-shaft planetary stirrer are too high, the load of the equipment is too heavy, the stirring paddle of the three-shaft planetary stirrer cannot rotate or the heat generation abrasion is too large, and if the revolution and rotation speeds of the three-shaft planetary stirrer are too low, the stirring time is prolonged, the efficiency is too low and the stirring effect is not good; if the stirring temperature is too low, the diffusion of additive molecules is not facilitated, and the wetting of the negative electrode material is further influenced, and if the temperature is too high, the additive is rapidly volatilized, and the wetting of the negative electrode material during subsequent stirring is also influenced.
S300: adding solvent into the second mixture and stirring under vacuum condition
In the step, a solvent is added to the second mixed material and stirred under a vacuum condition, so that a first mixed slurry with a solid content of 80-90 wt% is obtained. Specifically, the solid content of the first mixed slurry may be 80 wt%, 82 wt%, 84 wt%, 86 wt%, 88 wt%, 90 wt%. The solvent may be at least one of deionized water and NMP. The inventor finds that controlling the solid content of the first mixed slurry to be 80 wt% to 90 wt% is beneficial to improving the shearing friction effect between powder particles, and further promotes the wetting of the particle surfaces. The solvent adopts deionized water, so that the production cost can be greatly reduced, and the requirement on the quality of the slurry can be met; in addition, NMP with a small contact angle with the cathode active material can be adopted, so that the wettability can be well improved, and the cathode slurry with higher quality can be obtained.
According to an embodiment of the invention, the revolution speed of the three-axis planetary stirrer can be 5-20 rpm, the rotation speed can be 15-60 rpm, the stirring time can be 10-15 min, the stirring temperature can be 55-70 ℃, and the vacuum degree under the vacuum condition can be-90-30 kPa. Specifically, the revolution speed of the three-shaft planetary stirrer can be 5rpm, 7rpm, 10rpm, 12rpm, 15rpm, 17rpm and 20 rpm; the rotation speed may be 15rpm, 20rpm, 25rpm, 30rpm, 35rpm, 40rpm, 45rpm, 50rpm, 55rpm, 60 rpm; the time can be 10min, 11min, 12min, 13min, 14min, 15 min; the temperature can be 55 deg.C, 57 deg.C, 60 deg.C, 62 deg.C, 65 deg.C, 67 deg.C, 70 deg.C; the vacuum degree can be-90 kPa, -85kPa, -80kPa, -75kPa, -70kPa, -65kPa, -60kPa, -55kPa, -50kPa, -45kPa, -40kPa, -35kPa, -30 kPa. The stirring temperature can be controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer. The inventor finds that the stirring at the temperature can increase the contact between the powder particle surface and the solvent molecules, promote the powder particle diffusion in the solvent and facilitate the wetting, and simultaneously, because of the existence of the solvent, the additive is easy to dissolve with the solvent, and the volatilization of the additive can be avoided. If the revolution and rotation speeds of the three-axis planetary stirrer are too high, the load of the equipment is too heavy, the stirring paddle of the three-axis planetary stirrer cannot rotate or the heat generation abrasion is too large, and if the revolution and rotation speeds of the three-axis planetary stirrer are too low, the stirring time is prolonged, the efficiency is too low and the stirring effect is not good; if the stirring temperature is too high, the high molecular component structure in the slurry can be deformed or damaged, the too high temperature has higher requirements on the sealing and bearing strength of the equipment, and the too low temperature cannot achieve the effect of improving the infiltration of the powder particles. The main purpose of the vacuum environment is to remove the bubbles in the powder particles and slurry, the requirement of the vacuum degree is too high, the requirement of the equipment is increased, and the purpose of removing the bubbles is not achieved when the vacuum degree is too low.
S400: adding a solvent into the first mixed slurry and continuously stirring under a vacuum condition
In the step, a solvent is added to the first mixed slurry and stirring is continued under a vacuum condition, so that a second mixed slurry with a solid content of 60 wt% to 72 wt% is obtained. Specifically, the solid content of the second mixed slurry may be 60 wt%, 62 wt%, 64 wt%, 66 wt%, 68 wt%, 70 wt%, 72 wt%. The inventor finds that the solid content of the second mixed slurry is controlled to be 60-72 wt% and the high-strength shearing kneading effect of the three-shaft planetary mixer is combined, so that the kneading shearing effect among wetting powder particles is very strong, the agglomerated particles are favorably dispersed, and meanwhile, the thickening agent particles start to be stripped and dissolved layer by layer through the strong kneading shearing effect.
According to an embodiment of the invention, the revolution speed of the three-axis planetary stirrer can be 15-25 rpm, the rotation speed can be 45-75 rpm, the stirring time can be 40-65 min, the stirring temperature can be 55-70 ℃, and the vacuum degree under the vacuum condition can be-90-30 kPa. Specifically, the revolution speed of the three-shaft planetary stirrer can be 15rpm, 18rpm, 20rpm, 23rpm and 25 rpm; the rotation speed can be 45rpm, 50rpm, 55rpm, 60rpm, 65rpm, 70rpm and 75 rpm; the time can be 40min, 45min, 50min, 55min, 60 min; the temperature can be 55 deg.C, 57 deg.C, 60 deg.C, 62 deg.C, 65 deg.C, 67 deg.C, 70 deg.C; the vacuum degree can be-90 kPa, -85kPa, -80kPa, -75kPa, -70kPa, -65kPa, -60kPa, -55kPa, -50kPa, -45kPa, -40kPa, -35kPa, -30 kPa. The stirring temperature can be controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer. The inventors have found that stirring in the above temperature range is more advantageous for peeling and dissolving the thickener. If the revolution and rotation speeds of the three-axis planetary stirrer are too high, the load of the equipment is too heavy, the stirring paddle of the three-axis planetary stirrer cannot rotate or the heat generation abrasion is too large, and if the revolution and rotation speeds of the three-axis planetary stirrer are too low, the stirring time is prolonged, the efficiency is too low and the stirring effect is not good; if the stirring temperature is too high, the structure of the high molecular components in the slurry can be deformed or damaged, the sealing and bearing strength of the equipment is higher in requirement due to the too high temperature, and the effect of improving the particle agglomeration and dispersion and the thickener dissolution cannot be achieved due to the too low temperature. The main purpose of the vacuum environment is to remove the bubbles in the powder particles and slurry, the requirement of the vacuum degree is too high, the requirement of the equipment is increased, and the purpose of removing the bubbles is not achieved when the vacuum degree is too low.
S500: adding the binder and the solvent into the second mixed slurry and continuously stirring under the vacuum condition
In the step, a binder and a solvent are added to the second mixed slurry and stirring is continued under a vacuum condition, so that a third mixed slurry with a solid content of 53 wt% to 58 wt% is obtained. Specifically, the solid content of the third mixed slurry may be 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%. The binder may be at least one selected from SBR, LA132, LA 133. The mass ratio of the binder to the first mixed material can be (1-5): 100, for example, may be 1: 100,2: 100,3: 100,4: 100,5: 100. the inventor finds that controlling the solid content of the third mixed slurry to be 53 wt% to 58 wt% is beneficial to better dispersing the binder and the particles in the solvent under the high-intensity shearing kneading action of the three-shaft planetary mixer, and promotes complete dissolution of the thickening agent to obtain uniformly and stably dispersed slurry. The binders SBR, LA132, and LA133 can be present in an aqueous solvent or an oil NMP solvent very stably, and at the same time, can provide a good binding force between the negative electrode active material and the copper foil base material, and the amount of the binder added within the above-mentioned mass range has little adverse effect on the electrical properties of the battery, and is very suitable as a binder for a negative electrode.
According to an embodiment of the invention, the revolution speed of the three-axis planetary stirrer can be 5-20 rpm, the rotation speed can be 15-60 rpm, the stirring time can be 25-35 min, the stirring temperature can be 20-35 ℃, and the vacuum degree under the vacuum condition can be-90-30 kPa. Specifically, the revolution speed of the three-shaft planetary stirrer can be 5rpm, 8rpm, 10rpm, 13rpm, 15rpm, 17rpm and 20 rpm; the rotation speed may be 15rpm, 20rpm, 25rpm, 30rpm, 35rpm, 40rpm, 45rpm, 50rpm, 55rpm, 60 rpm; the time can be 25min, 28min, 30min, 33min, 35 min; the temperature can be 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C; the vacuum degree can be-90 kPa, -85kPa, -80kPa, -75kPa, -70kPa, -65kPa, -60kPa, -55kPa, -50kPa, -45kPa, -40kPa, -35kPa, -30 kPa. The stirring temperature can be controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer. The inventor finds that the temperature is mainly used for cooling down the temperature of the slurry, so that the discharge viscosity consistency of the slurry is improved. If the revolution and rotation speeds of the three-axis planetary stirrer are too high, the load of the equipment is too heavy, the stirring paddle of the three-axis planetary stirrer cannot rotate or the heat generation abrasion is too large, and if the revolution and rotation speeds of the three-axis planetary stirrer are too low, the stirring time is prolonged, the efficiency is too low and the stirring effect is not good; if the temperature of stirring is too high, be unfavorable for follow-up thick liquids shipment temperature's control, viscosity uniformity when influencing thick liquids shipment, and the temperature crosses lowly can influence stirring effect, and in addition, the temperature crosses lowly and stirs required energy consumption and will rise, and is unfavorable for the viscosity and the uniformity of control thick liquids equally. The main purpose of the vacuum environment is to remove the bubbles in the powder particles and slurry, the requirement of the vacuum degree is too high, the requirement of the equipment is increased, and the purpose of removing the bubbles is not achieved when the vacuum degree is too low.
S600: adding the solvent into the third mixed slurry and continuously stirring under the vacuum condition
In this step, a solvent is added to the third mixed slurry and stirring is continued under vacuum conditions to obtain a negative electrode slurry having a viscosity value of 3000 to 8000 mPas, and for example, 3000 mPas, 3500 mPas, 4000 mPas, 4500 mPas, 5000 mPas, 5500 mPas, 6000 mPas, 6500 mPas, 7000 mPas, 7500 mPas, 8000 mPas can be obtained. Specifically, the viscosity value of the negative electrode slurry may be determined according to the stability of the slurry and the coating requirements.
According to an embodiment of the invention, the revolution speed of the three-axis planetary stirrer can be 5-15 rpm, the rotation speed can be 15-45 rpm, the stirring time can be 25-35 min, the stirring temperature can be 20-35 ℃, and the vacuum degree under the vacuum condition can be-90-30 kPa. Specifically, the revolution speed of the three-shaft planetary stirrer can be 5rpm, 7rpm, 10rpm, 12rpm and 15 rpm; the rotation speed can be 15rpm, 20rpm, 25rpm, 30rpm, 35rpm, 40rpm and 45 rpm; the time can be 25min, 28min, 30min, 32min, 35 min; the temperature can be 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C; the vacuum degree can be-90 kPa, -85kPa, -80kPa, -75kPa, -70kPa, -65kPa, -60kPa, -55kPa, -50kPa, -45kPa, -40kPa, -35kPa, -30 kPa. The stirring temperature can be controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer. The inventor finds that if the revolution and rotation speeds of the three-shaft planetary stirrer are too high, the load of the equipment is too heavy, the stirring paddle of the three-shaft planetary stirrer cannot rotate or the heat generation abrasion is too large, and if the revolution and rotation speeds of the three-shaft planetary stirrer are too low, the stirring time is prolonged, the efficiency is too low and the stirring effect is not good; if the stirring temperature is too high, the control of the viscosity of the slurry and the consistency of the slurry are not facilitated, and if the temperature is too low, the stirring effect is influenced, in addition, the energy consumption required by stirring when the temperature is too low is increased, and the control of the viscosity and the consistency of the slurry are also not facilitated. The main purpose of the vacuum environment is to remove the bubbles in the powder particles and slurry, the requirement of the vacuum degree is too high, the requirement of the equipment is increased, and the purpose of removing the bubbles is not achieved when the vacuum degree is too low.
According to the method for preparing the cathode slurry, disclosed by the embodiment of the invention, the cathode active material, the conductive agent and the thickening agent are supplied to the three-axis planetary mixer for mixing and stirring, so that the macro mixing among the powder is realized, and the opening of powder particle agglomeration and the infiltration of the powder particle surface in subsequent high-viscosity stirring are facilitated. Simultaneously, the mixing and stirring are carried out in a three-shaft planetary stirrer, and compared with the traditional double-planetary stirrer without a high-speed dispersion plate, the high-speed dispersion plate is prevented from high-speed shearing damage to the molecular structure of the thickening agent in the slurry and damage to the subsequent adhesive, and the stability of the slurry and the adhesive force of a pole piece are favorably improved. Furthermore, the revolution paddle of the three-axis planetary mixer has stronger torque force than the double-planet revolution paddle, so that the surface infiltration of powder particles and the shearing kneading action of slurry are facilitated, the stirring time is further shortened, and high-viscosity kneading stirring with higher solid content can be performed. The additive is beneficial to improving the wettability of the surface of the powder particles, and is further beneficial to the dispersion of the powder particles after the solvent is subsequently added. The solid content of the first mixed slurry is controlled to be 80 wt% -90 wt%, so that the shearing friction effect among powder particles is improved, and the wetting of the particle surfaces is further promoted. The solid content of the second mixed slurry is controlled to be 60 wt% -72 wt%, and the high-strength shearing kneading effect of the triaxial planetary mixer is combined, so that the kneading shearing effect among the wetting powder particles is very strong, agglomerated particles are favorably dispersed, and meanwhile, the thickening agent particles start to be stripped and dissolved layer by layer through the strong kneading shearing effect. Controlling the solid content of the third mixed slurry to be 53-58 wt%, under the high-strength shearing kneading action of a three-axis planetary mixer, facilitating the binder and particles to be better dispersed in the solvent, promoting the thickener to be completely dissolved to obtain uniformly dispersed and stable slurry, and then adjusting the viscosity to obtain the negative electrode slurry with the viscosity value of 3000-8000 mPa & s. Therefore, the method can effectively solve the problem of infiltration of the negative active material and the solvent in the initial stirring stage, obviously shorten the stirring time of the slurry and improve the viscosity consistency of the slurry.
In still another aspect of the present invention, the present invention provides a negative electrode slurry, which is prepared by the above method for preparing a negative electrode slurry according to an embodiment of the present invention. Therefore, the negative electrode slurry has the advantages that the component particles are uniformly dispersed, the viscosity consistency and the stability are higher, and the coating appearance and the binding power of the slurry are improved. It should be noted that the features and advantages described above for the method of preparing the anode slurry are also applicable to the anode slurry, and are not described herein again.
In another aspect of the present invention, the present invention provides a lithium ion battery, according to an embodiment of the present invention, a negative electrode of the lithium ion battery is prepared by using the above negative electrode slurry. Therefore, the binding power of the negative electrode slurry and the current collector in the negative electrode is strong, the negative electrode has good charge and discharge performance due to the fact that the particles of all components in the negative electrode slurry are uniformly dispersed, the performance of the lithium ion battery can be obviously improved, and meanwhile, the cost of the lithium ion battery can be further reduced due to the fact that the production cost of the negative electrode slurry is low. It should be noted that the features and advantages described above for the negative electrode slurry are also applicable to the lithium ion battery, and are not described herein again.
The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.
Example 1
(1) Mixing the negative active material artificial graphite, the conductive agent super conductive carbon and the thickening agent CMC powder according to a mass ratio of 96.5: 1.0: 1.0, adding the mixture into a three-shaft planetary stirrer for mixing and stirring, wherein the revolution speed of the three-shaft planetary stirrer is 8rpm, the rotation speed of the three-shaft planetary stirrer is 24rpm, and the stirring time is 9min to obtain a first mixed material;
(2) adding 1, 3-butanediol serving as an additive into the first mixed material and stirring, wherein the mass ratio of the additive to the first mixed material is 0.5: 100, the revolution speed of the three-axis planetary stirrer is 10rpm, the rotation speed is 30rpm, the stirring time is 10min, and the stirring temperature is 25 ℃, so as to obtain a second mixed material;
(3) adding solvent deionized water into the second mixed material, and stirring under vacuum condition, wherein the revolution speed of the three-shaft planetary stirrer is 15rpm, the rotation speed is 45rpm, the stirring time is 10min, the stirring temperature is 60 ℃, and the vacuum degree under vacuum condition is-90 kPa, so as to obtain a first mixed slurry with the solid content of 86 wt%;
(4) adding solvent deionized water into the first mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-axis planetary stirrer is 20rpm, the rotation speed is 60rpm, the stirring time is 50min, the stirring temperature is 60 ℃, and the vacuum degree under the vacuum condition is-90 kPa, so that second mixed slurry with the solid content of 67 wt% is obtained;
(5) adding a binder SBR emulsion and solvent deionized water into the second mixed slurry, and continuously stirring under a vacuum condition, wherein the mass ratio of the binder SBR emulsion to the first mixed material is 1.5: 100, the revolution speed of the three-shaft planetary stirrer is 10rpm, the rotation speed is 30rpm, the stirring time is 30min, the stirring temperature is 25 ℃, and the vacuum degree under the vacuum condition is-90 kPa, so as to obtain a third mixed slurry with the solid content of 56 wt%;
(6) and adding deionized water serving as a solvent into the third mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-axis planetary stirrer is 15rpm, the rotation speed is 45rpm, the stirring time is 25min, the stirring temperature is 25 ℃, and the vacuum degree under the vacuum condition is-90 kPa, so that the negative electrode slurry with the viscosity value of 6000mPa & s is obtained, and the detection result of the negative electrode slurry is shown in Table 1.
In each step, the stirring temperature is controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer.
Example 2
(1) Mixing natural graphite serving as a negative electrode active material, a conductive agent carbon nano tube and a thickening agent CMC powder according to a mass ratio of 92: 4: 2, adding the mixture into a three-shaft planetary stirrer for mixing and stirring, wherein the revolution speed of the three-shaft planetary stirrer is 5rpm, the rotation speed of the three-shaft planetary stirrer is 30rpm, and the stirring time is 5min to obtain a first mixed material;
(2) adding acetone serving as an additive into the first mixed material and stirring, wherein the mass ratio of the acetone serving as the additive to the first mixed material is 0.1: 100, the revolution speed of the three-axis planetary stirrer is 5rpm, the rotation speed is 45rpm, the stirring time is 15min, and the stirring temperature is 0 ℃, so as to obtain a second mixed material;
(3) adding solvent deionized water into the second mixed material, and stirring under vacuum condition, wherein the revolution speed of the three-shaft planetary stirrer is 5rpm, the rotation speed is 60rpm, the stirring time is 12min, the stirring temperature is 55 ℃, and the vacuum degree under vacuum condition is-70 kPa, so as to obtain a first mixed slurry with the solid content of 80 wt%;
(4) adding solvent deionized water into the first mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-shaft planetary stirrer is 15rpm, the rotation speed is 75rpm, the stirring time is 40min, the stirring temperature is 55 ℃, and the vacuum degree under the vacuum condition is-70 kPa, so that second mixed slurry with the solid content of 60 wt% is obtained;
(5) adding a binder SBR emulsion and solvent deionized water into the second mixed slurry, and continuously stirring under a vacuum condition, wherein the mass ratio of the binder SBR emulsion to the first mixed material is 1: 100, the revolution speed of the three-shaft planetary stirrer is 5rpm, the rotation speed is 60rpm, the stirring time is 25min, the stirring temperature is 20 ℃, and the vacuum degree under the vacuum condition is-70 kPa, so that third mixed slurry with the solid content of 53 wt% is obtained;
(6) adding deionized water as a solvent into the third mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-axis planetary stirrer is 10rpm, the rotation speed is 30rpm, the stirring time is 30min, the stirring temperature is 20 ℃, and the vacuum degree under the vacuum condition is-70 kPa, so that the negative electrode slurry with the viscosity value of 3000mPa & s is obtained, and the detection result of the negative electrode slurry is shown in Table 1.
In each step, the stirring temperature is controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer.
Example 3
(1) Mixing the hard carbon of the negative active material, graphene serving as a conductive agent and CMC powder serving as a thickening agent according to a mass ratio of 98: 0.5: 0.5, adding the mixture into a three-shaft planetary stirrer for mixing and stirring, wherein the revolution speed of the three-shaft planetary stirrer is 10rpm, the rotation speed of the three-shaft planetary stirrer is 15rpm, and the stirring time is 10min to obtain a first mixed material;
(2) adding an additive ethanol into the first mixed material and stirring, wherein the mass ratio of the additive to the first mixed material is 5: 100, the revolution speed of the three-axis planetary stirrer is 15rpm, the rotation speed is 15rpm, the stirring time is 20min, and the stirring temperature is 40 ℃ to obtain a second mixed material;
(3) adding solvent deionized water into the second mixed material, and stirring under vacuum condition, wherein the revolution speed of the three-shaft planetary stirrer is 20rpm, the rotation speed is 15rpm, the stirring time is 15min, the stirring temperature is 70 ℃, and the vacuum degree under vacuum condition is-60 kPa, so as to obtain a first mixed slurry with the solid content of 90 wt%;
(4) adding solvent deionized water into the first mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-shaft planetary stirrer is 25rpm, the rotation speed is 45rpm, the stirring time is 65min, the stirring temperature is 70 ℃, and the vacuum degree under the vacuum condition is-60 kPa, so that second mixed slurry with the solid content of 72 wt% is obtained;
(5) adding a binder SBR emulsion and solvent deionized water into the second mixed slurry, and continuously stirring under a vacuum condition, wherein the mass ratio of the binder SBR emulsion to the first mixed material is 5: 100, the revolution speed of the three-shaft planetary stirrer is 20rpm, the rotation speed is 15rpm, the stirring time is 35min, the stirring temperature is 35 ℃, and the vacuum degree under the vacuum condition is-60 kPa, so that a third mixed slurry with the solid content of 58 wt% is obtained;
(6) adding deionized water as a solvent into the third mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-axis planetary stirrer is 5rpm, the rotation speed is 15rpm, the stirring time is 35min, the stirring temperature is 35 ℃, and the vacuum degree under the vacuum condition is-60 kPa, so that the negative electrode slurry with the viscosity value of 8000mPa & s is obtained, and the detection result of the negative electrode slurry is shown in Table 1.
In each step, the stirring temperature is controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer.
Example 4
(1) Mixing the negative active material soft carbon, conductive graphite serving as a conductive agent and CMC powder serving as a thickening agent according to a mass ratio of 94: 2: 1.5 adding the mixture into a three-shaft planetary stirrer for mixing and stirring, wherein the revolution speed of the three-shaft planetary stirrer is 9rpm, the rotation speed of the three-shaft planetary stirrer is 20rpm, and the stirring time is 8min to obtain a first mixed material;
(2) adding an additive NMP into the first mixed material and stirring, wherein the mass ratio of the additive to the first mixed material is 3: 100, the revolution speed of the three-axis planetary stirrer is 12rpm, the rotation speed is 35rpm, the stirring time is 18min, and the stirring temperature is 30 ℃, so as to obtain a second mixed material;
(3) adding solvent deionized water into the second mixed material, and stirring under vacuum condition, wherein the revolution speed of the three-axis planetary stirrer is 10rpm, the rotation speed is 50rpm, the stirring time is 14min, the stirring temperature is 65 ℃, and the vacuum degree under vacuum condition is-50 kPa, so as to obtain a first mixed slurry with the solid content of 84 wt%;
(4) adding solvent deionized water into the first mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-axis planetary stirrer is 18rpm, the rotation speed is 65rpm, the stirring time is 45min, the stirring temperature is 65 ℃, and the vacuum degree under the vacuum condition is-50 kPa, so as to obtain a second mixed slurry with the solid content of 70 wt%;
(5) adding a binder SBR emulsion and solvent deionized water into the second mixed slurry, and continuously stirring under a vacuum condition, wherein the mass ratio of the binder SBR emulsion to the first mixed material is 3: 100, the revolution speed of the three-shaft planetary stirrer is 15rpm, the rotation speed is 30rpm, the stirring time is 28min, the stirring temperature is 28 ℃, and the vacuum degree under the vacuum condition is-50 kPa, so as to obtain a third mixed slurry with the solid content of 55 wt%;
(6) and adding deionized water serving as a solvent into the third mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-axis planetary stirrer is 9rpm, the rotation speed is 25rpm, the stirring time is 28min, the stirring temperature is 28 ℃, and the vacuum degree under the vacuum condition is-50 kPa, so that the negative electrode slurry with the viscosity value of 5000mPa & s is obtained, and the detection result of the negative electrode slurry is shown in Table 1.
In each step, the stirring temperature is controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer.
Example 5
(1) Mixing the negative active material artificial graphite and natural graphite with the conductive agent super conductive carbon and the thickening agent CMC powder according to the mass ratio of 60: 34: 2.5: 1.7 adding the mixture into a three-shaft planetary stirrer for mixing and stirring, wherein the revolution speed of the three-shaft planetary stirrer is 7rpm, the rotation speed of the three-shaft planetary stirrer is 27rpm, and the stirring time is 7min to obtain a first mixed material;
(2) adding ethanol serving as an additive into the first mixed material and stirring, wherein the mass ratio of the additive to the first mixed material is 4.2: 100, the revolution speed of the three-axis planetary stirrer is 11rpm, the rotation speed is 38rpm, the stirring time is 17min, and the stirring temperature is 28 ℃, so as to obtain a second mixed material;
(3) adding solvent deionized water into the second mixed material, and stirring under vacuum condition, wherein the revolution speed of the three-axis planetary stirrer is 11rpm, the rotation speed is 38rpm, the stirring time is 11min, the stirring temperature is 62 ℃, and the vacuum degree under vacuum condition is-30 kPa, so as to obtain a first mixed slurry with the solid content of 87 wt%;
(4) adding solvent deionized water into the first mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-axis planetary stirrer is 17rpm, the rotation speed is 63rpm, the stirring time is 57min, the stirring temperature is 62 ℃, and the vacuum degree under the vacuum condition is-30 kPa, so that second mixed slurry with the solid content of 69 wt% is obtained;
(5) adding a binder SBR emulsion and solvent deionized water into the second mixed slurry, and continuously stirring under a vacuum condition, wherein the mass ratio of the binder SBR emulsion to the first mixed material is 3.5: 100, the revolution speed of the three-shaft planetary stirrer is 17rpm, the rotation speed is 48rpm, the stirring time is 27min, the stirring temperature is 28 ℃, and the vacuum degree under the vacuum condition is-30 kPa, so that a third mixed slurry with the solid content of 57 wt% is obtained;
(6) adding deionized water as a solvent into the third mixed slurry, and continuously stirring under a vacuum condition, wherein the revolution speed of a three-shaft planetary stirrer is 11rpm, the rotation speed is 38rpm, the stirring time is 28min, the stirring temperature is 28 ℃, and the vacuum degree under the vacuum condition is-30 kPa, so that the negative electrode slurry with the viscosity value of 7000 mPas is obtained, and the detection result of the negative electrode slurry is shown in Table 1.
In each step, the stirring temperature is controlled by introducing constant-temperature circulating water with corresponding temperature into the interlayer of the three-axis planetary stirrer.
Comparative example 1
The wet stirring process is adopted to prepare the slurry, and comprises the following steps:
mixing artificial graphite, super conductive carbon, CMC powder and SBR according to a mass ratio of 96.5: 1.0: 1.0: 1.5, preparing for standby, wherein the stirrer adopts a double-planet stirrer;
adding CMC powder and deionized water solvent into a double-planet stirrer, vacuumizing, and stirring for 180min under the conditions of dispersion speed of 1000rpm, revolution speed of a stirring paddle of 25rpm and stirring temperature of 25 ℃ until CMC is completely dissolved to prepare CMC glue solution;
adding super conductive carbon and SBR into the CMC sol, vacuumizing, and stirring for 60min at the dispersion speed of 1000rpm, the revolution speed of a stirring paddle of 20rpm and the stirring temperature of 25 ℃ to obtain a black glue solution;
adding artificial graphite into the black colloid liquid, vacuumizing, and stirring for 120min under the conditions that the dispersion speed is 1200rpm, the revolution speed of a stirring paddle is 25rpm, and the stirring temperature is 25 ℃ to obtain uniform slurry;
and testing the viscosity of the obtained uniform slurry, and if the viscosity does not meet the requirement, adding a part of deionized water solvent to adjust the viscosity of the slurry, wherein the specific conditions are as follows: vacuumizing, and stirring for 30min under the conditions that the dispersion speed is 1000rpm, the revolution speed of a stirring paddle is 20rpm, and the stirring temperature is 25 ℃ to obtain the slurry with the viscosity value of 6000 mPa.s.
Comparative example 2
The dry stirring process is adopted to prepare the slurry, and comprises the following steps:
mixing artificial graphite, super conductive carbon, CMC powder and SBR according to a mass ratio of 96.5: 1.0: 1.0: 1.5, preparing for standby, wherein the stirrer adopts a double-planet stirrer;
adding artificial graphite into a double-planet stirrer, then sequentially adding super conductive carbon and CMC powder, and stirring for 10min under the conditions that the dispersion speed is 800rpm, the revolution speed of a stirring paddle is 10rpm and the stirring temperature is 25 ℃ to prepare mixed powder;
adding a deionized water solvent into the mixed powder, vacuumizing, and stirring for 180min under the conditions that the dispersion speed is 1200rpm, the revolution speed of a stirring paddle is 25rpm, and the stirring temperature is 25 ℃ to prepare first mixed slurry;
adding SBR emulsion into the first mixed slurry, vacuumizing, and stirring for 30min under the conditions that the dispersion speed is 1000rpm, the revolution speed of a stirring paddle is 20rpm, and the stirring temperature is 25 ℃ to obtain uniform slurry;
and testing the viscosity of the obtained uniform slurry, and if the viscosity does not meet the requirement, adding a part of deionized water solvent to adjust the viscosity of the slurry, wherein the specific conditions are as follows: vacuumizing, and stirring for 30min under the conditions that the dispersion speed is 1000rpm, the revolution speed of a stirring paddle is 20rpm, and the stirring temperature is 25 ℃ to obtain the slurry with the viscosity value of 6000 mPa.s.
And (4) analyzing results:
the slurries of examples 1 to 5, comparative example 1 and comparative example 2 were tested for particle size and standing settling time under the same conditions, and the test results are shown in table 1. it can be seen from table 1 that the slurries obtained in examples 1 to 5 are more uniform, the standing settling time is longer, and the time required for stirring the slurries is shorter than those of comparative documents 1 and 2.
TABLE 1 test results for slurries of examples 1-5, comparative example 1 and comparative example 2
| Slurry stirring time | Particle size D50 of the slurry | Standing and settling time of slurry | |
| Example 1 | 134min | 13.0μm | 132h |
| Example 2 | 127min | 13.8μm | 130h |
| Example 3 | 175min | 12.5μm | 132h |
| Example 4 | 136min | 12.8μm | 130h |
| Example 5 | 147min | 13.6μm | 135h |
| Comparative example 1 | 390min | 13μm | 80h |
| Comparative example 2 | 250min | 15μm | 96h |
The slurry of examples 1 to 5, comparative example 1 and comparative example 2 was coated and dried under the same conditions to prepare pole pieces, and then the adhesion of the current collectors in the pole pieces (180 ° peel test) and the resistance of the lithium battery were tested, and the test results are shown in table 2, and it can be seen from table 2 that the adhesion of the current collectors in the pole pieces obtained in examples 1 to 5 is larger and the resistance of the pole pieces is smaller.
TABLE 2 test results of pole pieces of examples 1-5, comparative example 1 and comparative example 2
| Current collector adhesive force | Pole piece resistor | |
| Example 1 | 13～15N/m | 0.08～0.15Ω/100μm |
| Example 2 | 13～14N/m | 0.06～0.13Ω/100μm |
| Example 3 | 14～16N/m | 0.08～0.14Ω/100μm |
| Example 4 | 13～15N/m | 0.09～0.15Ω/100μm |
| Example 5 | 12～14N/m | 0.06～0.12Ω/100μm |
| Comparative example 1 | 4～7N/m | 0.12～0.35Ω/100μm |
| Comparative example 2 | 4～8N/m | 0.10～0.30Ω/100μm |
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (12)
1. A method of preparing an anode slurry, comprising:
(1) adding a negative electrode active material, a conductive agent and a thickening agent into a three-axis planetary mixer for mixing and stirring so as to obtain a first mixed material;
(2) adding an additive into the first mixed material and stirring to obtain a second mixed material;
(3) adding a solvent into the second mixed material and stirring under a vacuum condition so as to obtain a first mixed slurry with the solid content of 80-90 wt%;
(4) adding the solvent into the first mixed slurry and continuously stirring under a vacuum condition so as to obtain a second mixed slurry with the solid content of 60-72 wt%;
(5) adding a binder and the solvent into the second mixed slurry and continuously stirring under a vacuum condition so as to obtain a third mixed slurry with the solid content of 53-58 wt%;
(6) adding the solvent into the third mixed slurry and continuously stirring under a vacuum condition so as to obtain negative electrode slurry with a viscosity value of 3000-8000 mPa & s,
in the step (1), the revolution speed of the three-axis planetary stirrer is 5-10 rpm, the rotation speed is 15-30 rpm, the stirring time is 5-10 min, and the mass ratio of the negative electrode active material to the conductive agent to the thickening agent is (92-98): (0.5-4): (0.5-2), the negative active material is at least one selected from artificial graphite, natural graphite, hard carbon and soft carbon, the conductive agent is at least one selected from super conductive carbon, carbon nanotubes, graphene and conductive graphite, and the thickening agent is at least one selected from CMC powder and CMC solution;
in the step (2), the additive is at least one selected from acetone, ethanol, 1, 3-butanediol and NMP, and the mass ratio of the additive to the first mixed material is (0.1-5): 100.
2. the method according to claim 1, wherein in the step (2), the revolution speed of the three-axis planetary mixer is 5 to 15rpm, the rotation speed is 15 to 45rpm, the mixing time is 10 to 20min, and the mixing temperature is 0 to 40 ℃.
3. The method according to claim 1, wherein in the step (3), the revolution speed of the three-axis planetary mixer is 5 to 20rpm, the rotation speed is 15 to 60rpm, the mixing time is 10 to 15min, and the mixing temperature is 55 to 70 ℃.
4. The method of claim 3, wherein in step (3), the solvent is at least one of deionized water and NMP.
5. The method according to claim 1, wherein in the step (4), the revolution speed of the three-axis planetary mixer is 15 to 25rpm, the rotation speed is 45 to 75rpm, the mixing time is 40 to 65min, and the mixing temperature is 55 to 70 ℃.
6. The method according to claim 1, wherein in the step (5), the revolution speed of the three-axis planetary mixer is 5 to 20rpm, the rotation speed is 15 to 60rpm, the mixing time is 25 to 35min, and the mixing temperature is 20 to 35 ℃.
7. The method according to claim 6, wherein in the step (5), the binder is at least one selected from SBR, LA132 and LA 133.
8. The method according to claim 6 or 7, wherein in the step (5), the mass ratio of the binder to the first mixed material is (1-5): 100.
9. the method according to claim 1, wherein in the step (6), the revolution speed of the three-axis planetary mixer is 5 to 15rpm, the rotation speed is 15 to 45rpm, the mixing time is 25 to 35min, and the mixing temperature is 20 to 35 ℃.
10. The method according to claim 1, wherein in the step (3), the step (4), the step (5) and the step (6), the vacuum degree of the vacuum condition is-90 kPa to-30 kPa respectively and independently.
11. A negative electrode slurry, characterized in that the negative electrode slurry is prepared by the method of any one of claims 1 to 10.
12. A lithium ion battery, wherein a negative electrode of the lithium ion battery is prepared by using the negative electrode slurry according to claim 11.
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| CN112755872A (en) * | 2019-11-05 | 2021-05-07 | 东莞市沃泰通新能源有限公司 | Preparation method of battery cathode slurry |
| CN111463490A (en) * | 2020-03-20 | 2020-07-28 | 梅州市量能新能源科技有限公司 | Preparation method of battery glue solution |
| CN112201766B (en) * | 2020-09-30 | 2021-12-17 | 蜂巢能源科技有限公司 | Negative electrode slurry and preparation method and application thereof |
| CN112713257B (en) * | 2020-12-29 | 2022-04-08 | 湖北亿纬动力有限公司 | Preparation method of negative electrode slurry and negative electrode slurry |
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| CN114725378A (en) * | 2022-04-22 | 2022-07-08 | 湖南钠方新能源科技有限责任公司 | Negative electrode slurry and preparation method thereof, negative electrode plate and secondary battery |
| CN115090142B (en) * | 2022-07-22 | 2023-03-10 | 郑州中科新兴产业技术研究院 | Lithium-sulfur battery positive electrode material, slurry and homogenizing method thereof |
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