CN114247360A

CN114247360A - Mixing method of lithium battery solid material

Info

Publication number: CN114247360A
Application number: CN202111564329.7A
Authority: CN
Inventors: 刘密; 何巍; 徐悦斌; 李跃飞; 艾思伟
Original assignee: Ningbo Eve Chuang Energy Lithium Battery Co ltd
Current assignee: Ningbo Eve Chuang Energy Lithium Battery Co ltd
Priority date: 2021-12-20
Filing date: 2021-12-20
Publication date: 2022-03-29

Abstract

The invention provides a mixing method of a lithium battery solid material, which comprises the following steps: (1) introducing gas into the air mixing tank, and adjusting the pressure; (2) conveying the main material, the conductive agent and the binder to an air mixing tank through gas respectively to be in a suspension state for mixing; (3) the mixed solid is conveyed to the stirring tank through the gas to be stirred, so that the uniformly mixed material is obtained.

Description

Mixing method of lithium battery solid material

Technical Field

The invention belongs to the technical field of lithium ion batteries, and relates to a mixing method of a lithium battery solid material.

Background

The lithium ion battery has the advantages of high open-circuit voltage, high energy density, low self-discharge rate, no memory effect, environmental friendliness, multiple cycle times, quick charge and discharge and the like. The lithium ion battery is an important chemical power source, and is widely applied to the fields of portable small-sized electrical appliances such as mobile phones, notebook computers and cameras, as well as aerospace, and gradually moves to the field of electric automobile power.

The lithium ion battery is generally produced by mixing solid materials in the preparation process, and is mainly added into a stirring tank through a pipeline and mixed in the stirring tank; the mixing is not uniform, the time is long, and the solid appearance is easy to damage.

CN107785540A discloses a process for mixing the negative electrode of a lithium ion battery, wherein graphite is baked at 300-400 ℃ under normal pressure to remove oily substances on the surface, the negative electrode and Super-P are poured into a charging bucket and are added into a roller bottle for ball milling at the same time, and the rotating speed is controlled to be more than 60 rmp; heating purified water to 80 deg.C, pouring into a power mixer; adding SBR and deionized water; adding the dry materials of the negative electrode in four average sequences, adding purified water while adding materials, wherein the interval is 28-32 minutes each time; high-speed stirring is carried out after the fourth feeding is carried out for 30 plus or minus 2 minutes; connecting the power mixer to vacuum, and keeping the vacuum degree at-0.09 to 0.10 Mpa; taking 500 ml of slurry, and measuring the viscosity by using a viscometer; and taking the negative electrode material out of the power mixer, grinding, sieving and flowing into a slurry drawing operation process.

CN108305987A discloses a blending process of lithium ion battery negative electrode slurry, a lithium ion battery negative electrode sheet and a lithium ion battery, wherein the process is simple and easy to operate, but in the actual production process, the viscosity parameter of the finally prepared suspension slurry is an important index for determining whether the slurry can be coated, and when we only use the solid content as the basis, the viscosity of the slurry fluctuates greatly, which cannot meet the coating requirement, even results in slurry scrapping.

CN110787668A discloses an improved mixing method in the process of preparing slurry for lithium ion batteries, in which all solid materials are added into a stirring apparatus to be stirred and mixed to obtain a mixed material; then adding the solvent into the mixed materials in batches, and respectively stirring and uniformly mixing to obtain slurry; the solid material comprises an active substance, a binder and a conductive agent; the viscosity of the slurry is 4000cps to 9000cps, and the solid content is 60% to 65%.

The technical scheme has the problems of complex operation, long time consumption or serious damage to the material appearance, so that the development of the mixing method which is simple to operate, short in time consumption and free of damage to the material appearance is very necessary.

Disclosure of Invention

The invention aims to provide a mixing method of a solid material of a lithium battery, which mixes the solid material in a suspension state through gas, can greatly shorten the mixing time and can avoid the damage of grinding to the shape of the material.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a mixing method of a lithium battery solid material, which comprises the following steps:

(1) introducing gas into the air mixing tank, and adjusting the pressure;

(2) conveying the main material, the conductive agent and the binder to an air mixing tank through gas respectively to be in a suspension state for mixing;

(3) and conveying the mixed solid to a stirring tank through gas, and stirring to obtain a uniformly mixed material.

The lithium ion battery is produced by mixing solid materials, and is mainly added into a stirring tank through a pipeline and mixed in the stirring tank, and the method has the problems of uneven mixing, long time and easy damage to the solid appearance.

Preferably, the gas of step (1) comprises air.

Preferably, the pressure of the introduced gas in the step (1) is 0.01-0.4 MPa, for example: 0.01MPa, 0.05MPa, 0.1MPa, 0.2MPa or 0.4MPa, etc.

Preferably, the particle size of the main material in the step (2) is 0.1-50 μm, for example: 0.1 μm, 1 μm, 5 μm, 10 μm, 20 μm or 50 μm, preferably 20 to 30 μm.

In the mixing method, the particle size of the main material influences the mixing effect, the particle size of the main material is controlled to be 20-30 mu m, the mixing effect is good, and if the particle size of the main material is too large, the particle size is increased; if the particle size of the main material is too small, the particle size of the resulting slurry will also be higher.

Preferably, the main material of step (2) includes any one of a lithium-based material, a carbon-based material, or a silicon-based material, or a combination of at least two thereof.

Preferably, the conductive agent in the step (2) is a solid conductive agent.

Preferably, the conductive agent in step (2) comprises any one or a combination of at least two of conductive carbon black, carbon nanotubes or graphite.

Preferably, the binder of step (2) is a solid binder.

Preferably, the binder in the step (2) comprises polyvinylidene fluoride and/or styrene butadiene rubber.

Preferably, the mixing time in the step (2) is 1-10 min, for example: 1min, 3min, 5min, 8min or 10min, preferably 5-10 min.

In the mixing method, the mixing time can influence the mixing effect, the mixing time is controlled to be 5-10 min, the mixing effect is good, if the mixing time is too short, the uniformity of the material prepared by mixing is poor, and if the mixing time is too long, the mixing effect is not improved, but the problems of energy consumption increase and resource waste are caused.

Preferably, the stirring time in the step (3) is 20-40min, for example: 20min, 25min, 30min, 35min or 40min and the like.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, the powdery solid material is suspended by the gas, and is mixed and stirred by the airflow flow, so that the stirring can be completed in the conveying process, the material mixing time is greatly shortened, and the production efficiency is improved.

(2) The granularity of the slurry prepared by the mixing method can reach below 37 mu m, the fineness can reach below 23 mu m, and the content difference of elements on the upper layer and the lower layer can reach below 0.53 percent.

Drawings

FIG. 1 is a process flow diagram of the mixing process described in example 1 of the present invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides a mixing method of a solid material of a lithium battery, which comprises the following steps:

(1) introducing the silicon-based material with the particle size of 20 microns, the carbon-based material, the conductive carbon black and the polyvinylidene fluoride into an air mixing tank through pipelines respectively;

(2) and introducing air into the air mixing tank, adjusting the pressure to be 0.02MPa to enable the powdery solid material to suspend and mix for 5min, conveying the mixed solid to the stirring tank through the air, and stirring for 30min to obtain a uniformly mixed material.

The process flow diagram of the mixing method described in this example is shown in fig. 1.

Example 2

(1) respectively introducing the carbon-based material with the particle size of 30 mu m, the silicon-based material, the conductive carbon black and the styrene butadiene rubber into an air mixing tank through pipelines;

(2) and introducing air into the air mixing tank, adjusting the pressure to be 0.02MPa to enable the powdery solid material to suspend and mix for 3min, conveying the mixed solid to the stirring tank through the air, and stirring for 30min to obtain a uniformly mixed material.

Example 3

(1) introducing the silicon-based material with the particle size of 10 mu m, the carbon-based material, the conductive carbon black and the polyvinylidene fluoride into an air mixing tank through pipelines respectively;

Example 4

(1) introducing the silicon-based material with the particle size of 40 mu m, the carbon-based material, the conductive carbon black and the polyvinylidene fluoride into an air mixing tank through pipelines respectively;

Example 5

Example 6

(2) and introducing air into the air mixing tank, adjusting the pressure to be 0.02MPa to enable the powdery solid material to suspend and mix for 12min, conveying the mixed solid to the stirring tank through the air, and stirring for 30min to obtain a uniformly mixed material.

Comparative example 1

This comparative example differs from example 1 only in that all the materials were stirred directly in a stirred tank for 30min, the other conditions and parameters being exactly the same as in example 1.

And (3) testing dispersion indexes: and taking the lower slurry to test the granularity and the fineness by using a fineness plate, and taking the upper and lower slurries to test the element content by an EDS (enhanced dispersive Spectroscopy) energy spectrum.

The test results are shown in table 1:

TABLE 1

	Particle size/. mu.m	Fineness/. mu.m	Difference in content of upper and lower layer elements
				Example 1	36	18	0.15％
Example 2	37	20	0.18％
				Example 3	30	21	0.48％
Example 4	32	23	0.53％
				Example 5	37	22	0.43％
Example 6	35	18	0.15％
				Comparative example 1	88	28	3.21％

As can be seen from Table 1, the particle size of the slurry obtained by the mixing method of the present invention can be as low as 37 μm, the fineness can be as low as 23 μm, and the difference in the contents of the upper and lower elements can be as low as 0.53% as shown in examples 1 to 6.

Comparing the embodiment 1 with the embodiments 3-4, the particle size of the main material can influence the mixing effect, the particle size of the main material is controlled to be 20-30 μm, the mixing effect is good, and if the particle size of the main material is too large, the particle size can be increased; if the particle size of the main material is too small, the particle size is also high.

Compared with the examples 5 to 6, the mixing time can affect the mixing effect, the mixing time is controlled to be 5-10 min, the mixing effect is good, if the mixing time is too short, the uniformity of the materials prepared by mixing is poor, and if the mixing time is too long, the mixing effect is not improved, but the problems of energy consumption increase and resource waste can be caused.

Compared with the comparative example 1, the method has the advantages that the powdery solid material is suspended by the gas, the mixture and the stirring are carried out through the airflow flow, the granularity and the fineness of the slurry obtained through the mixing are obviously reduced compared with the slurry obtained through the traditional direct stirring, the prepared slurry is stable, the content difference of elements in an upper layer and a lower layer is small, the stability is obviously improved, the mixing method can complete the stirring in the conveying process, the material mixing time is greatly shortened, and the production efficiency is improved.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims

1. A mixing method of solid materials for lithium batteries, characterized in that the mixing method comprises the following steps:

(1) introducing gas into the air mixing tank;

2. The mixing method of claim 1, wherein the gas of step (1) comprises air.

3. The mixing method according to claim 1 or 2, wherein the pressure of the gas introduced in the step (1) is 0.01 to 0.4 MPa.

4. The mixing method according to any one of claims 1 to 3, wherein the main material of step (2) comprises any one of a lithium-based material, a carbon-based material, or a silicon-based material, or a combination of at least two thereof.

5. The mixing method according to any one of claims 1 to 4, wherein the particle size of the main material in the step (2) is 0.1 to 50 μm, preferably 20 to 30 μm.

6. The mixing method according to any one of claims 1 to 5, wherein the conductive agent in the step (2) is a solid conductive agent.

7. The mixing method according to any one of claims 1 to 6, wherein the conductive agent of step (2) comprises any one of conductive carbon black, carbon nanotubes or graphite or a combination of at least two thereof.

8. The mixing method according to any one of claims 1 to 7, wherein the binder in the step (2) is a solid binder.

9. The mixing method according to any one of claims 1 to 8, wherein the binder of step (2) comprises polyvinylidene fluoride and/or styrene butadiene rubber;

preferably, the mixing time in the step (2) is 1-10 min, preferably 5-10 min.

10. The mixing method according to any one of claims 1 to 9, wherein the stirring time in step (3) is 20 to 40 min.