Method for improving fluidization effect of negative electrode material particles of secondary battery

Abstract

The embodiment of the invention relates to a method for improving the fluidization effect of negative electrode material particles of a secondary battery. The method comprises the following steps: giving charges to secondary battery negative electrode material powder particles; wherein the secondary battery negative electrode material powder particles are non-magnetic particles; the secondary battery negative electrode material powder particles endowed with charges are subjected to airflow stirring in a fluidized bed and are simultaneously matched with magnetic stirring, so that the secondary battery negative electrode material powder particles obtain kinetic energy dispersion through airflow; and the secondary battery negative electrode material powder particles are dispersed to form a fluidized state through the Lorentz force of the magnetic field on the secondary battery negative electrode material powder particles endowed with the charges and the electrostatic repulsive force among the powder particles with the charges with the same polarity, so that the fluidization effect of the secondary battery negative electrode material particles is improved.

Description

Technical Field

[0001] The invention relates to the technical field of powder material dispersion, and in particular to a method for improving the fluidization effect of secondary battery negative electrode material particles. Background Art

[0002] Particle "agglomeration" refers to the phenomenon that multiple particles adhere together to form "agglomerates". The main reason for agglomeration is the result of the interaction of surface energy such as charge, moisture, and van der Waals force carried by the particles. The finer the particles, the larger the specific surface area, the greater the surface energy, and the greater the probability of agglomeration. When the powder material is ultra-fine to a certain degree, the distance between the particles is extremely short, and the van der Waals force between the particles is much greater than the gravity of the particles themselves. Therefore, such ultra-fine particles tend to attract each other and agglomerate. Hydrogen bonds, adsorption wet bridges and other chemical bonds on the surface of ultra-fine particles can also easily cause particles to adhere to each other and aggregate. In the process of ultra-fine powder materials, due to impact, friction and reduction in particle size, a large amount of positive or negative charge accumulates on the surface of the newly formed ultra-fine particles. Some of the protrusions on the surface of these particles are positively charged, and some are negatively charged. These charged particles are extremely unstable. In order to be stable, they attract each other, and the sharp corners contact and connect with each other, causing the particles to agglomerate. The main force of this process is electrostatic force. When the relative humidity of the air exceeds 65%, water vapor begins to condense on the surface of particles and between particles, and the agglomeration effect is greatly enhanced due to the formation of liquid bridges between particles. In addition, during the crushing process, the powder material absorbs a large amount of mechanical energy or thermal energy, so that the surface of the newly formed ultrafine particles has a very high surface energy, and the particles are in an extremely unstable state. In order to reduce the surface energy, particles often reach a stable state by gathering together and getting close to each other, which is also easy to cause particle agglomeration.

[0003] For materials that need to be prepared in a high temperature environment, such as negative electrode materials for secondary batteries, when there is agglomeration in the powder, the packing density of the green body will decrease and the shape will be uneven. At the same time, since the sintering temperature between particles in the agglomerate is higher than the sintering temperature between agglomerates, the required sintering temperature will be increased. For powders with agglomeration, the increase in sintering temperature can easily lead to overburning and secondary recrystallization, which will have extremely adverse consequences on the performance of the sintered body. Summary of the invention

[0004] The purpose of the present invention is to provide a method for improving the fluidization effect of secondary battery negative electrode material particles, so as to improve the problem that the secondary battery negative electrode material particles are easy to agglomerate and difficult to disperse.

[0005] To this end, an embodiment of the present invention provides a method for improving the fluidization effect of secondary battery negative electrode material particles, the method comprising:

[0006] Imparting electric charge to the secondary battery negative electrode material powder particles; wherein the secondary battery negative electrode material powder particles are non-magnetic particles;

[0007] The charged secondary battery negative electrode material powder particles are subjected to air flow stirring in a fluidized bed and combined with magnetic stirring, so that the secondary battery negative electrode material powder particles not only obtain kinetic energy dispersion through the air flow, but also disperse the secondary battery negative electrode material powder particles into a fluidized state through the Lorentz force of the magnetic field on the charged secondary battery negative electrode material powder particles and the electrostatic repulsion between powder particles with the same polarity charge, so as to improve the fluidization effect of the secondary battery negative electrode material particles.

[0008] Preferably, the step of imparting charge to the secondary battery negative electrode material powder particles specifically includes:

[0009] The secondary battery negative electrode material powder particles are charged by any one of contact charging, induction charging, arc charging, friction charging, and corona charging.

[0010] Preferably, the magnetic force of the magnetic stirring is generated by an electromagnet, wherein the magnetic field strength is adjustable and the magnetic field direction is variable.

[0011] Preferably, the fluidized bed is a vertical vapor deposition fluidized bed.

[0012] Preferably, the method for improving the fluidization effect of secondary battery negative electrode material particles is performed in an oxygen-free environment.

[0013] Preferably, the particle size of the secondary battery negative electrode material powder particles is micrometer-level or nanometer-level.

[0014] Further preferably, the secondary battery negative electrode material powder particles are any one of silicon-based material powder particles, carbon-based material powder particles or silicon-carbon material powder particles.

[0015] Preferably, while or after the charged secondary battery negative electrode material powder particles are subjected to air flow stirring in a fluidized bed and magnetic stirring, the method further includes: heat treating the secondary battery negative electrode material powder particles.

[0016] The method for improving the fluidization effect of the negative electrode material particles of a secondary battery provided by an embodiment of the present invention first charges the powder particles of the negative electrode material of the secondary battery. By giving a charge to the non-magnetic particles, the particles have a charge characteristic. Such a charge can cause electrostatic repulsion between the particles, thereby helping to disperse the particles and prevent aggregation between the particles. Then, the particles are stirred by airflow and magnetic stirring. In the fluidized bed, the charged negative electrode material powder particles of the secondary battery are stirred by airflow, and the action of the airflow will give the particles kinetic energy, so that the particles are continuously dispersed and collided, thereby promoting the interaction between the particles, which helps to further prevent the accumulation and agglomeration of particles. Combined with airflow stirring is magnetic stirring, which applies Lorentz force to charged particles by cooperating with a magnetic field. This force will drive the particles to move in the fluidized bed, and particles with the same polarity charge will generate electrostatic repulsion. This helps to further disperse the particles and prevent agglomeration. Therefore, by combining charge and magnetic stirring, the charged negative electrode material powder particles of the secondary battery can be more effectively dispersed and formed into a fluidized state under the action of airflow and magnetic force. Such a fluidized state can enhance the contact between particles and fluid, thereby improving the fluidization effect in the preparation and mixing of secondary battery negative electrode materials. The technical solution of the present invention utilizes the combined effects of charge imparting, air flow stirring and magnetic stirring, effectively improving the fluidization characteristics of secondary battery negative electrode material particles, improving the dispersion and fluidity of the material, and helping to improve production efficiency and quality in the fields of secondary battery manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a method for improving the fluidization effect of secondary battery negative electrode material particles provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0019] The embodiment of the present invention provides a method for improving the fluidization effect of the negative electrode material particles of a secondary battery, and the method is performed in an oxygen-free environment. The main method steps are as follows: Figure 1 As shown, including:

[0020] Step 110, imparting electric charge to the secondary battery negative electrode material powder particles;

[0021] The secondary battery negative electrode material powder particles are non-magnetic particles. The step of imparting electric charge to the secondary battery negative electrode material powder particles specifically includes imparting electric charge to the secondary battery negative electrode material powder particles by any one of contact charging, induction charging, arc charging, friction charging, and corona charging.

[0022] In actual operation, the powder material is passed into the charging bin and the power is turned on to give the particles a charge, which can be achieved by but not limited to the following equipment:

[0023] Electrostatic Spray Charger: This device is usually used to atomize powder materials and charge the particles through an electric field during the spraying process. The powder material is sprayed out and separated by the electric field and the charge separator, and the charged particles are collected.

[0024] Electrostatic Powder Sprayer: A device used to spray powder materials with an electric charge. The powder material is accelerated and sprayed out by an electric field, thereby acquiring an electric charge.

[0025] Static Electricity Charger: This device transfers the charge to the powder material by bringing the powder material into contact with a charged object or electrode, giving the particles a charge through electrostatic contact.

[0026] Electrostatic Dust Separator: This device is commonly used in industrial environments to separate electrically charged dust from a gas stream. The dust is acted upon by an electric field and is collected while the gas is released.

[0027] Charging Bar: Transfers charge to powder material through electric field effect. Charging bar is usually made of charged material and transfers charge by contacting with powder material.

[0028] In practical applications, it is necessary to select suitable equipment according to the specific application and material properties to ensure safe operation and obtain the expected charging effect.

[0029] In step 120, the charged secondary battery negative electrode material powder particles are subjected to air flow stirring in a fluidized bed while being magnetically stirred, so that the secondary battery negative electrode material powder particles not only obtain kinetic energy dispersion through the air flow, but also disperse the secondary battery negative electrode material powder particles into a fluidized state through the Lorentz force of the magnetic field on the charged secondary battery negative electrode material powder particles and the electrostatic repulsion between powder particles with the same polarity charge, so as to enhance the fluidization effect of the secondary battery negative electrode material particles.

[0030] Specifically, the magnetic force of the magnetic stirring is generated by an electromagnet, wherein the magnetic field strength is adjustable and the magnetic field direction is variable. The fluidized bed is preferably a vertical vapor deposition fluidized bed.

[0031] While or after the charged secondary battery negative electrode material powder particles are subjected to air flow stirring and magnetic stirring in a fluidized bed, the secondary battery negative electrode material powder particles may be heat treated.

[0032] The particle size of the secondary battery negative electrode material powder particles of the present invention is micrometer-level or nanometer-level, specifically any one of silicon-based material powder particles, carbon-based material powder particles or silicon-carbon material powder particles.

[0033] In order to better understand the technical solution provided by the present invention, the specific application of the method for improving the fluidization effect of the negative electrode material particles of a secondary battery of the present invention is respectively described below with multiple specific examples.

[0034] Example 1

[0035] This embodiment provides a method for improving the fluidization effect of nano-silicon powder, and the specific preparation process is as follows.

[0036] 1) At room temperature, place the nano-silicon powder material in an electrostatic charger, maintain a nitrogen atmosphere, start the power supply to charge the nano-silicon powder material for 30 minutes, and then collect the powder material.

[0037] 2) The collected powder material is passed into a fluidized bed deposition furnace with a magnetic field, and the magnetic field is started. The nano-silicon powder material forms a fluidized state under the combined action of the airflow and the magnetic field. The temperature is raised to 400°C at a rate of 3°C / min, and the material is cooled and discharged after being kept at a constant temperature for 3 hours.

[0038] Example 2

[0039] This embodiment provides a method for fluidizing nano silicon carbon powder, and the specific preparation process is as follows.

[0040] 1) At room temperature, place the nano silicon carbon powder material in a spray charger, maintain a nitrogen atmosphere, start the power supply to charge the nano silicon carbon powder material particles for 45 minutes, and then collect the powder material.

[0041] 2) The collected nano-silicon carbon powder material is passed into a fluidized bed deposition furnace with a magnetic field, and the magnetic field is started. The powder material forms a fluidized state under the combined action of the airflow and the magnetic field, and the temperature is increased to 600°C at 4°C / min, and the material is cooled and discharged after being kept at a constant temperature for 2 hours.

[0042] Example 3

[0043] This embodiment provides a method for fluidizing micron silicon-carbon powder, and the specific preparation process is as follows.

[0044] 1) At room temperature, the micron silicon carbon powder material is placed in an electrostatic precipitator, a nitrogen atmosphere is maintained, and a power supply is started to impart a charge to the micron silicon carbon powder material particles for 30 minutes, after which the powder material is collected.

[0045] 2) The collected micron silicon-carbon powder material is passed into a fluidized bed deposition furnace with a magnetic field, and the magnetic field is started. The powder material forms a fluidized state under the combined action of the airflow and the magnetic field, and the temperature is raised to 500°C at 5°C / min, and the material is cooled and discharged after being kept at a constant temperature for 3 hours.

[0046] Example 4

[0047] This embodiment provides a method for fluidizing micron silicon powder, and the specific preparation process is as follows.

[0048] 1) At room temperature, place the micron silicon powder material into a plasma ejector, maintain a nitrogen atmosphere, start the power supply to give a charge to the micron silicon powder material particles for 20 minutes, and then collect the powder material.

[0049] 2) The collected micron silicon powder material is passed into a fluidized bed deposition furnace with a magnetic field, and the magnetic field is started. The powder material forms a fluidized state under the combined action of the airflow and the magnetic field, and the temperature is increased to 500°C at a rate of 5°C / min, and the material is cooled and discharged after being kept at a constant temperature for 3 hours.

[0050] Example 5

[0051] This embodiment provides a method for fluidizing nano silicon carbon powder, and the specific preparation process is as follows.

[0052] 1) At room temperature, the nano silicon carbon powder material particles are charged by a charge rod, and then the powder material is collected.

[0053] 2) The collected nano-silicon carbon powder material is passed into a fluidized bed deposition furnace with a magnetic field, and the magnetic field is started. The powder material forms a fluidized state under the combined action of the airflow and the magnetic field, and the temperature is increased to 600°C at 4°C / min, and the material is cooled and discharged after being kept at a constant temperature for 2 hours.

[0054] The method for improving the fluidization effect of the negative electrode material particles of a secondary battery provided by an embodiment of the present invention first charges the powder particles of the negative electrode material of the secondary battery. By giving a charge to the non-magnetic particles, the particles have a charge characteristic. Such a charge can cause electrostatic repulsion between the particles, thereby helping to disperse the particles and prevent aggregation between the particles. Then, the particles are stirred by airflow and magnetic stirring. In the fluidized bed, the charged negative electrode material powder particles of the secondary battery are stirred by airflow, and the action of the airflow will give the particles kinetic energy, so that the particles are continuously dispersed and collided, thereby promoting the interaction between the particles, which helps to further prevent the accumulation and agglomeration of particles. Combined with airflow stirring is magnetic stirring, which applies Lorentz force to charged particles by cooperating with a magnetic field. This force will drive the particles to move in the fluidized bed, and particles with the same polarity charge will generate electrostatic repulsion. This helps to further disperse the particles and prevent agglomeration. Therefore, by combining charge and magnetic stirring, the charged negative electrode material powder particles of the secondary battery can be more effectively dispersed and formed into a fluidized state under the action of airflow and magnetic force. Such a fluidized state can enhance the contact between particles and fluid, thereby improving the fluidization effect in the preparation and mixing of secondary battery negative electrode materials. The technical solution of the present invention utilizes the combined effects of charge imparting, air flow stirring and magnetic stirring, effectively improving the fluidization characteristics of secondary battery negative electrode material particles, improving the dispersion and fluidity of the material, and helping to improve production efficiency and quality in the fields of secondary battery manufacturing.

[0055] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the fluidization effect of secondary battery negative electrode material particles, characterized in that: The method comprises: Imparting electric charge to the secondary battery negative electrode material powder particles; wherein the secondary battery negative electrode material powder particles are non-magnetic particles; The charged secondary battery negative electrode material powder particles are subjected to air flow stirring in a fluidized bed and combined with magnetic stirring, so that the secondary battery negative electrode material powder particles not only obtain kinetic energy dispersion through the air flow, but also disperse the secondary battery negative electrode material powder particles into a fluidized state through the Lorentz force of the magnetic field on the charged secondary battery negative electrode material powder particles and the electrostatic repulsion between powder particles with the same polarity charge, so as to improve the fluidization effect of the secondary battery negative electrode material particles.

2. The method for improving the fluidization effect of secondary battery negative electrode material particles according to claim 1, characterized in that: The step of imparting charge to the secondary battery negative electrode material powder particles specifically includes: The secondary battery negative electrode material powder particles are charged by any one of contact charging, induction charging, arc charging, friction charging, and corona charging.

3. The method for improving the fluidization effect of secondary battery negative electrode material particles according to claim 1, characterized in that: The magnetic force of the magnetic stirring is generated by an electromagnet, wherein the magnetic field strength is adjustable and the magnetic field direction is variable.

4. The method for improving the fluidization effect of secondary battery negative electrode material particles according to claim 1, characterized in that: The fluidized bed is a vertical vapor deposition fluidized bed.

5. The method for improving the fluidization effect of secondary battery negative electrode material particles according to claim 1, characterized in that: The method for improving the fluidization effect of secondary battery negative electrode material particles is performed in an oxygen-free environment.

6. The method for improving the fluidization effect of secondary battery negative electrode material particles according to claim 1, characterized in that: The particle size of the secondary battery negative electrode material powder particles is micrometer-level or nanometer-level.

7. The method for improving the fluidization effect of secondary battery negative electrode material particles according to claim 6, characterized in that: The secondary battery negative electrode material powder particles are specifically any one of silicon-based material powder particles, carbon-based material powder particles or silicon-carbon material powder particles.

8. The method for improving the fluidization effect of secondary battery negative electrode material particles according to claim 1, characterized in that: The method further comprises: heat treating the secondary battery negative electrode material powder particles after being charged, while stirring the secondary battery negative electrode material powder particles with air flow and magnetic force in a fluidized bed or after that.

Images