WO2024120497A1 - Aqueous homogenization process for positive electrode system of lithium-ion battery, slurry and lithium-ion battery - Google Patents

Abstract

An aqueous homogenization process for a positive electrode system of a lithium-ion battery, a slurry and a lithium-ion battery. The process comprises the steps of: mixing a positive electrode main material and a conductive agent to obtain a mixed powder, and wetting the mixed powder with water to obtain a first slurry; mixing an aqueous adhesive glue solution, an aqueous conductive agent glue solution and the first slurry, and then subjecting the resultant mixture to vacuum stirring and vacuum dispersion to obtain a second slurry; and mixing the aqueous adhesive glue solution, water and the second slurry, and then subjecting the resultant mixture to vacuum stirring and vacuum dispersion to obtain a positive electrode slurry.

Description

Aqueous homogenization process for lithium-ion battery positive electrode system, slurry and lithium-ion battery

This application claims the priority of the Chinese patent application filed with the China Patent Office on December 7, 2022, with application number 202211567635.0. The entire contents of the above application are incorporated by reference into this application.

Technical Field

The present application relates to the field of battery technology, and more particularly to an aqueous homogenization process for a lithium-ion battery positive electrode system, a slurry and a lithium-ion battery for a lithium-ion battery positive electrode system.

Background technique

Lithium-ion batteries have the advantages of long cycle life, high energy density and environmental protection, and are widely used in electric vehicles and energy storage. The preparation process of lithium-ion batteries includes homogenization, coating, rolling, assembly and formation, among which the homogenization process is the first process, and also the most important and core process. The quality of the slurry plays a decisive role in the subsequent coating and the performance of the final lithium-ion battery.

At present, the positive electrode stirring of lithium-ion batteries in the industry is generally an oil-based process, that is, N-methylpyrrolidone is used as a solvent. This solvent has a pungent odor, is harmful to the human body if exposed for a long time, is costly and has strong hygroscopicity, so the oil-based process has high requirements for the battery manufacturing environment and is costly. Therefore, the water-based process using deionized water as a solvent has become the research direction in the industry. Deionized water has low cost, is non-toxic and has low requirements for the production environment, but the solubility of water in active substances and conductive agents is much lower than that of N-methylpyrrolidone, making it difficult to directly disperse active substances and conductive agents in deionized water.

Currently, there are three main types of homogenization processes for positive electrode slurry: (1) dry homogenization process, first the dry powders of active material, conductive agent and binder are mixed evenly, then an appropriate amount of solvent is added for kneading, and finally the solvent is added for high-speed dispersion to obtain slurry; (2) semi-dry homogenization process, generally the dry powders of active material and conductive agent are mixed evenly, then the glue prepared in advance is added to the above dry powder for kneading, and finally the solvent is added for high-speed dispersion to obtain slurry; (3) wet homogenization process, generally the glue is prepared first, then the conductive agent is added to the glue for dispersion, and then the active material is added for dispersion, and finally the slurry is obtained by high-speed dispersion.

When these three homogenization processes are applied to water-based systems, it is found that: (1) In the dry homogenization process, the dry powder is easy to agglomerate during the first step of adding glue, which is not conducive to the dispersion of subsequent processes. The dispersion process requires a large shear force, which has high requirements on equipment and leads to increased production costs. (2) In the semi-dry homogenization process, kneading will cause the stirring paddle to scratch the cylinder wall, and the slurry will stick to the cylinder wall. The slurry cannot be squeezed and rubbed in time, and thus the particle size cannot be reduced. (3) In the wet homogenization process, the conductive agent has a large specific surface area and is easy to agglomerate in water. Most of the conductive agents are hydrophobic particles, which are more difficult to disperse than in oil-based binders. In addition, the solid content of the conductive agent in the conductive glue is relatively low, and the conductive agent cannot be dispersed by friction and extrusion. Therefore, the particle size of the conductive glue cannot be reduced, resulting in a large particle size of the slurry. In addition, the wet homogenization process is generally time-consuming. The above homogenization processes can prepare a non-sedimentation and stable slurry in an oil-based solvent system. However, it is difficult to prepare a slurry with small fineness and high stability when these three homogenization processes are applied to a water-based system.

Related art discloses a method for homogenizing the positive electrode of a lithium-ion battery, comprising the following steps: first, mixing water and a binder, and stirring; then, sequentially adding a conductive agent, stirring, adding a positive electrode active material, stirring, adding an additive, stirring; and finally, adding water to adjust the viscosity; the additive contains a lipophilic group. This technology adds an additive containing a lipophilic group to the positive electrode slurry, suppresses the pseudoplasticity of the binder, and makes the slurry viscosity and state stable, making it easy to apply. However, the slurry prepared by the method for homogenizing the positive electrode of a lithium-ion battery has a large fineness and low stability.

Related art discloses a method for preparing an aqueous super nano lithium iron phosphate battery. The lithium iron phosphate battery in this technology first prepares positive and negative electrode slurries, and then applies the obtained positive and negative electrode slurries to the surface of aluminum foil to obtain positive and negative electrode sheets, and then stacks the positive and negative electrode sheets and places them in a battery housing and injects electrolyte, and finally completes the formation and capacity separation steps to obtain a lithium iron phosphate battery. However, the preparation method of the aqueous super nano lithium iron phosphate battery mixes and homogenizes lithium iron phosphate powder particles with a conductive agent and an aqueous binder to obtain a positive electrode slurry, and the particle size of the prepared positive electrode rubber is large and the uniformity is poor.

Related technology discloses a water-based negative electrode sheet for a high-power lithium-ion battery and a preparation method thereof. This technology specifically discloses a material formula and formula ratio of a water-based negative electrode sheet for high-power lithium-ion power batteries, using pure water/deionized water as a solvent and a low-cost aqueous binder to prepare the negative electrode sheet; discloses a more efficient, more environmentally friendly, time- and cost-saving homogenization preparation process to solve the problems of agglomeration and sedimentation during the homogenization process; in addition, it discloses a coating parameter and rolling density of a high-power battery negative electrode sheet, thereby ensuring the consistency and low internal resistance of the high-power electrode sheet, eliminating the risk of peeling and falling of the electrode sheet, and achieving the high-power characteristics and consistency of the battery. However, the preparation process of the preparation method of the water-based negative electrode sheet for high-power lithium-ion batteries is complicated and the preparation efficiency is low.

The currently disclosed aqueous homogenization processes for lithium-ion battery positive electrode systems have certain defects, such as high particle size and low stability of the prepared positive electrode slurry, complex preparation method, low preparation efficiency, high preparation cost and high requirements on the production environment. Therefore, it is very important to develop and design a new aqueous homogenization process, slurry and lithium battery for lithium-ion battery positive electrode systems.

SUMMARY OF THE INVENTION

The present application provides an aqueous slurry process, slurry and lithium ion battery for a lithium ion battery positive electrode system to solve the above technical problems.

In a first aspect, the present application provides an aqueous homogenization process for a lithium-ion battery positive electrode system, the aqueous homogenization process comprising the following steps:

(1) mixing a positive electrode main material and a conductive agent to obtain a mixed powder, and soaking the mixed powder with water to obtain a wet first slurry;

(2) mixing the aqueous adhesive solution, the aqueous conductive agent solution and the first slurry obtained in step (1), and then simultaneously performing vacuum stirring and vacuum dispersion to obtain a wet second slurry;

(3) After mixing the aqueous adhesive solution, water and the second slurry obtained in step (2), vacuum stirring and vacuum dispersion are simultaneously performed to obtain a positive electrode slurry for a lithium-ion battery.

In a second aspect, the present application provides a positive electrode slurry for a lithium-ion battery, wherein the positive electrode slurry for a lithium-ion battery is prepared by the aqueous homogenization process described in the first aspect.

In a third aspect, the present application provides a lithium-ion battery, wherein the lithium-ion battery comprises the lithium-ion battery positive electrode slurry described in the second aspect.

Beneficial Effects

The lithium-ion battery positive electrode slurry prepared by the aqueous homogenization process of the lithium-ion battery positive electrode system described in the present application has low particle size and high stability. The aqueous homogenization process has a short time, high preparation efficiency, low preparation cost and low requirements on the production environment and production equipment.

Embodiments of the present invention

In view of the deficiencies in the related art, the present application provides an aqueous slurry process, slurry and lithium ion battery for a lithium ion battery positive electrode system.

In a first aspect, the present application provides an aqueous homogenization process for a lithium-ion battery positive electrode system, the aqueous homogenization process comprising the following steps:

(1) mixing a positive electrode main material and a conductive agent to obtain a mixed powder, and soaking the mixed powder with water to obtain a wet first slurry;

(2) after mixing the water-based adhesive solution, the water-based conductive agent solution and the first slurry obtained in step (1), vacuum stirring and vacuum dispersing are simultaneously performed to obtain a wet second slurry;

(3) After mixing the aqueous adhesive solution, water and the second slurry obtained in step (2), vacuum stirring and vacuum dispersion are simultaneously performed to obtain a positive electrode slurry for a lithium-ion battery.

In the aqueous slurrying process of the lithium ion battery positive electrode system described in the present application, in step (1), the positive electrode main material and the conductive agent are mixed, and then a small amount of water is added to wet them first, thereby avoiding the agglomeration of the mixed powder; in step (2), the aqueous adhesive glue, the aqueous conductive agent glue and the first slurry are mixed and scraped, and stirred and dispersed at a suitable solid content. The solid content will not make the slurry reach a kneading state, thereby avoiding the kneading process causing the stirring paddle to scratch the cylinder wall and stick to the cylinder, thereby avoiding the slurry sticking to the cylinder cannot be squeezed and rubbed in time, resulting in poor dispersion effect of the final lithium ion battery positive electrode slurry; in step (2), the aqueous adhesive glue, the aqueous conductive agent glue and the first slurry are evenly dispersed through a one-step glue adding process, which effectively reduces the investment cost of the slurry preparation process, the time of the aqueous slurrying process is short, the overall process efficiency is improved, and the stability and uniformity of the aqueous positive electrode system slurry are effectively guaranteed.

The lithium-ion battery positive electrode slurry prepared by the aqueous homogenization process of the lithium-ion battery positive electrode system described in the present application has low particle size and high stability. The aqueous homogenization process has a short time, high preparation efficiency, low preparation cost and low requirements on the production environment and production equipment.

In one embodiment, the mixing method in step (1) includes a first stirring.

In one embodiment, the first stirring speed is 15-30 rpm, and the time is 10-30 min.

The present application limits the first stirring speed to 15~30rpm, for example, it can be 15rpm, 16rpm, 17rpm, 18rpm, 19rpm, 20rpm, 21rpm, 22rpm, 23rpm, 24rpm, 25rpm, 26rpm, 27rpm, 28rpm, 29rpm or 30rpm, but it is not limited to the listed values, and other values not listed within the numerical range are also applicable.

The present application defines the first stirring time as 10-30 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min or 30 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

In one embodiment, the wetting method in step (1) includes a second stirring.

In one embodiment, the second stirring has a rotation speed of 15-30 rpm and a duration of 10-30 min.

The present application limits the second stirring speed to 15~30rpm, for example, it can be 15rpm, 16rpm, 17rpm, 18rpm, 19rpm, 20rpm, 21rpm, 22rpm, 23rpm, 24rpm, 25rpm, 26rpm, 27rpm, 28rpm, 29rpm or 30rpm, but it is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

The present application defines the second stirring time as 10-30 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min or 30 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

In one embodiment, the positive electrode main material in step (1) includes any one of a ternary positive electrode material, lithium iron phosphate, elemental sulfur or lithium manganate, or a combination of at least two of them. Typical but non-limiting combinations include a combination of a ternary positive electrode material and lithium iron phosphate, a combination of lithium iron phosphate and elemental sulfur, a combination of elemental sulfur and lithium manganate, or a combination of a ternary positive electrode material, lithium iron phosphate and elemental sulfur.

The ternary positive electrode material in the present application includes lithium nickel cobalt manganese oxide and/or lithium nickel cobalt aluminum oxide.

In one embodiment, the conductive agent in step (1) includes any one of conductive carbon black, conductive graphite, acetylene black or Ketjen black, or a combination of at least two of them. Typical but non-limiting combinations include a combination of conductive carbon black and conductive graphite, a combination of conductive graphite and acetylene black, a combination of acetylene black and Ketjen black, or a combination of conductive carbon black, conductive graphite and Ketjen black.

In one embodiment, the solid content of the first slurry in step (1) is 80-85wt%, for example, 80wt%, 80.5wt%, 81wt%, 81.5wt%, 82wt%, 82.5wt%, 83wt%, 83.5wt%, 84wt%, 84.5wt% or 85wt%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the mass ratio of the positive electrode main material to the conductive agent in the first slurry in step (1) is (90-99):(0.5-10), for example, it can be 90:0.5, 90:1, 90:2, 90:3, 90:4, 90:5, 90:6, 90:7, 90:8, 90:9, 90:10, 99:0.5, 99:7 or 99:10, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the mixing method in step (2) includes a third stirring.

In one embodiment, the third stirring has a rotation speed of 15-30 rpm and a duration of 10-30 min.

In the present application, the rotation speed of the third stirring is 15~30rpm, for example, it can be 15rpm, 16rpm, 17rpm, 18rpm, 19rpm, 20rpm, 21rpm, 22rpm, 23rpm, 24rpm, 25rpm, 26rpm, 27rpm, 28rpm, 29rpm or 30rpm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In the present application, the third stirring time is 10 to 30 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min or 30 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

In one embodiment, the rotation speed of the vacuum stirring in step (2) is 15-30 rpm, for example, it can be 15 rpm, 16 rpm, 17 rpm, 18 rpm, 19 rpm, 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm or 30 rpm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the rotation speed of the vacuum dispersion in step (2) is 500-800 rpm, for example, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm or 800 rpm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the vacuum degree of the vacuum stirring and vacuum dispersion in step (2) is -0.1~-0.085Mpa, for example, it can be -0.1Mpa, -0.098Mpa, -0.095Mpa, -0.092Mpa, -0.09Mpa, -0.088Mpa or -0.085Mpa, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the time for vacuum stirring and vacuum dispersion in step (2) is 3 to 5 hours, for example, 3 hours, 3.2 hours, 3.5 hours, 4 hours, 4.2 hours, 4.5 hours, 4.7 hours or 5 hours, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the water-based adhesive solution in step (2) includes a water-based adhesive and water, and the water-based adhesive includes any one of polyvinylidene fluoride adhesive, styrene butadiene rubber latex adhesive, carboxymethyl cellulose adhesive, polyacrylic acid adhesive, polyacrylonitrile adhesive or polyacrylate adhesive, or a combination of at least two of them. Typical but non-limiting combinations include a combination of polyvinylidene fluoride adhesive and styrene butadiene rubber latex adhesive, a combination of styrene butadiene rubber latex adhesive and carboxymethyl cellulose adhesive, a combination of polyacrylic acid adhesive and polyacrylonitrile adhesive, a combination of polyacrylonitrile adhesive and polyacrylate adhesive, or a combination of polyvinylidene fluoride adhesive, styrene butadiene rubber latex adhesive and carboxymethyl cellulose adhesive.

In one embodiment, the solid content of the aqueous adhesive solution in step (2) is 15-20wt%, for example, 15wt%, 15.5wt%, 16wt%, 16.5wt%, 17wt%, 17.5wt%, 18wt%, 18.5wt%, 19wt%, 19.5wt% or 20wt%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the aqueous conductive agent paste in step (2) includes an aqueous conductive agent and water, and the aqueous conductive agent includes any one of carbon nanofibers, carbon nanotubes or graphene, or a combination of at least two of them. Typical but non-limiting combinations include a combination of carbon nanofibers and carbon nanotubes, a combination of carbon nanotubes and graphene, a combination of carbon nanofibers and graphene, or a combination of carbon nanofibers, carbon nanotubes and graphene.

In one embodiment, the solid content of the aqueous conductive agent paste in step (2) is 5-10wt%, for example, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the solid content of the second slurry in step (2) is 70-77 wt%, for example, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt% or 77 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

In one embodiment, the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry of step (2) is (90-99):(0.5-10):(1-3):(0.5-10).

In step (2) of the present application, the mass ratio of the positive electrode main material to the conductive agent in the second slurry is (90~99):(0.5~10), for example, it can be 90:0.5, 90:1, 90:2, 90:3, 90:4, 90:5, 90:6, 90:7, 90:8, 90:9, 90:10, 99:0.5, 99:7 or 99:10, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In step (2) of the present application, the mass ratio of the positive electrode main material to the aqueous adhesive in the second slurry is (90~99):(1~3), for example, it can be 90:1, 90:2, 90:3, 99:1, 99:2 or 99:3, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In step (2) of the present application, the mass ratio of the positive electrode main material to the aqueous conductive agent in the second slurry is (90~99):(0.5~10), for example, it can be 90:0.5, 90:1, 90:2, 90:3, 90:4, 90:5, 90:6, 90:7, 90:8, 90:9, 90:10, 99:0.5, 99:7 or 99:10, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the mixing method in step (3) includes a fourth stirring.

In one embodiment, the fourth stirring has a rotation speed of 15-30 rpm and a time of 10-30 min.

In the present application, the fourth stirring speed is 15~30rpm, for example, it can be 15rpm, 16rpm, 17rpm, 18rpm, 19rpm, 20rpm, 21rpm, 22rpm, 23rpm, 24rpm, 25rpm, 26rpm, 27rpm, 28rpm, 29rpm or 30rpm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

In the present application, the fourth stirring time is 10 to 30 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min or 30 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

In one embodiment, the rotation speed of the vacuum stirring in step (3) is 15-30 rpm, for example, it can be 15 rpm, 16 rpm, 17 rpm, 18 rpm, 19 rpm, 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm or 30 rpm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the rotation speed of the vacuum dispersion in step (3) is 2500-3000 rpm, for example, it can be 2500 rpm, 2550 rpm, 2600 rpm, 2650 rpm, 2700 rpm, 2750 rpm, 2800 rpm, 2850 rpm, 2900 rpm, 2950 rpm or 3000 rpm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the vacuum degree of the vacuum stirring and vacuum dispersion in step (3) is -0.1~-0.085Mpa, for example, it can be -0.1Mpa, -0.098Mpa, -0.095Mpa, -0.092Mpa, -0.09Mpa, -0.088Mpa or -0.085Mpa, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the time for vacuum stirring and vacuum dispersion in step (3) is 1 to 3 hours, for example, 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, 2.2 hours, 2.5 hours, 2.7 hours or 3 hours, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the water-based adhesive solution in step (3) is the same as the water-based adhesive solution in step (2).

In one embodiment, the solid content of the lithium-ion battery positive electrode slurry in step (3) is 55-60wt%, for example, 55wt%, 56wt%, 57wt%, 58wt%, 59wt% or 60wt%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the viscosity of the lithium-ion battery positive electrode slurry in step (3) is 4000-8000cp, for example, 4000cp, 4500cp, 5000cp, 5500cp, 6000cp, 6500cp, 7000cp, 7500cp or 8000cp, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the fineness of the lithium-ion battery positive electrode slurry in step (3) is 10-20 μm, for example, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

In one embodiment, the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry in step (3) is (90-99):(0.5-10):(3-10):(0.5-10).

The mass ratio of the positive electrode main material to the conductive agent in the lithium ion battery positive electrode slurry in step (3) of the present application is (90~99):(0.5~10), for example, it can be 90:0.5, 90:1, 90:2, 90:3, 90:4, 90:5, 90:6, 90:7, 90:8, 90:9, 90:10, 99:0.5, 99:7 or 99:10, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

The mass ratio of the positive electrode main material to the aqueous adhesive in the lithium ion battery positive electrode slurry in step (3) of the present application is (90~99):(3~10), for example, it can be 90:3, 90:4, 90:5, 90:6, 90:7, 90:8, 90:9, 90:10, 99:3, 99:4, 99:5, 99:7 or 99:10, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

The mass ratio of the positive electrode main material to the aqueous conductive agent in the positive electrode slurry for the lithium ion battery in step (3) of the present application is (90~99):(0.5~10), for example, it can be 90:0.5, 90:1, 90:2, 90:3, 90:4, 90:5, 90:6, 90:7, 90:8, 90:9, 90:10, 99:0.5, 99:7 or 99:10, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

As an optional technical solution of the water system homogenization process described in the first aspect, the water system homogenization process comprises the following steps:

(1) mixing the positive electrode main material and the conductive agent by a first stirring process at a speed of 15-30 rpm for 10-30 min to obtain a mixed powder, and then infiltrating the mixed powder with water by a second stirring process at a speed of 15-30 rpm for 10-30 min to obtain a first slurry with a wet solid content of 80-85 wt %, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry is (90-99):(0.5-10);

(2) After mixing the aqueous adhesive solution with a solid content of 15-20wt%, the aqueous conductive agent solution with a solid content of 5-10wt% and the first slurry obtained in step (1) by a third stirring process at a speed of 15-30rpm for 10-30min, vacuum stirring at a speed of 15-30rpm and vacuum dispersion at a speed of 500-800rpm for 3-5h at a vacuum degree of -0.1-0.085Mpa are simultaneously performed to obtain a muddy second slurry with a solid content of 70-77wt%, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry is (90-99):(0.5-10):(1-3):(0.5-10);

(3) After mixing the aqueous adhesive solution and water obtained in step (2) by a fourth stirring process at a speed of 15-30 rpm for 10-30 min, vacuum stirring at a speed of 15-30 rpm and vacuum dispersion at a speed of 2500-3000 rpm are simultaneously performed for 1-3 h at a vacuum degree of -0.1-0.085 MPa to obtain a lithium ion battery positive electrode slurry with a solid content of 50-60 wt %, a viscosity of 4000-8000 cp and a fineness of 10-20 μm, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry is (90-99):(0.5-10):(3-10):(0.5-10).

In a second aspect, the present application provides a positive electrode slurry for a lithium-ion battery, wherein the positive electrode slurry for a lithium-ion battery is prepared by the aqueous homogenization process described in the first aspect.

In a third aspect, the present application provides a lithium-ion battery, wherein the lithium-ion battery comprises the lithium-ion battery positive electrode slurry described in the second aspect.

The technical solution of the present application is further illustrated by means of specific embodiments below.

Example 1

This embodiment provides an aqueous homogenization process for a lithium-ion battery positive electrode system, and the aqueous homogenization process comprises the following steps:

(1) mixing the positive electrode main material and the conductive agent by a first stirring process at a speed of 24 rpm for 20 min to obtain a mixed powder, and then infiltrating the mixed powder with water by a second stirring process at a speed of 20 rpm for 15 min to obtain a muddy first slurry with a solid content of 82 wt %, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry is 95:2;

(2) After mixing the aqueous adhesive solution with a solid content of 17 wt %, the aqueous conductive agent solution with a solid content of 8 wt % and the first slurry obtained in step (1) by a third stirring process at a rotation speed of 20 rpm for 20 min, vacuum stirring at a rotation speed of 24 rpm and vacuum dispersion at a rotation speed of 580 rpm were simultaneously performed for 3 h at a vacuum degree of -0.096 MPa to obtain a muddy second slurry with a solid content of 73 wt %, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry is 95:2:1:2;

(3) After mixing the aqueous adhesive solution and water obtained in step (2) with the second slurry obtained in step (2) by a fourth stirring process at a speed of 20 rpm for 20 min, vacuum stirring at a speed of 28 rpm and vacuum dispersion at a speed of 2700 rpm were simultaneously performed at a vacuum degree of -0.092 MPa for 2.5 h to obtain a lithium ion battery positive electrode slurry with a solid content of 55 wt%. The mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry was 95:2:3:2.

Example 2

This embodiment provides an aqueous homogenization process for a lithium-ion battery positive electrode system, and the aqueous homogenization process comprises the following steps:

(1) mixing the positive electrode main material and the conductive agent by a first stirring process at a rotation speed of 20 rpm for 15 min to obtain a mixed powder, and then infiltrating the mixed powder with water by a second stirring process at a rotation speed of 28 rpm for 13 min to obtain a muddy first slurry with a solid content of 81 wt %, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry is 98:5;

(2) After mixing the aqueous adhesive solution with a solid content of 18 wt %, the aqueous conductive agent solution with a solid content of 9 wt % and the first slurry obtained in step (1) by a third stirring process at a speed of 24 rpm for 25 min, vacuum stirring at a speed of 20 rpm and vacuum dispersion at a speed of 720 rpm were simultaneously performed at a vacuum degree of -0.088 MPa for 3.5 h to obtain a muddy second slurry with a solid content of 75 wt %, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry was 98:5:2:3;

(3) After mixing the aqueous adhesive solution and water obtained in step (2) with the second slurry obtained in step (2) by a fourth stirring process at a speed of 24 rpm for 25 min, vacuum stirring at a speed of 24 rpm and vacuum dispersion at a speed of 2600 rpm were simultaneously performed for 2 h at a vacuum degree of -0.1 MPa to obtain a lithium ion battery positive electrode slurry with a solid content of 57 wt%. The mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry was 98:5:4:3.

Example 3

This embodiment provides an aqueous homogenization process for a lithium-ion battery positive electrode system, and the aqueous homogenization process comprises the following steps:

(1) mixing the positive electrode main material and the conductive agent by a first stirring process at a speed of 28 rpm for 13 min to obtain a mixed powder, and then infiltrating the mixed powder with water by a second stirring process at a speed of 15 rpm for 30 min to obtain a muddy first slurry with a solid content of 83 wt %, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry is 93:6;

(2) After mixing the aqueous adhesive solution with a solid content of 19 wt %, the aqueous conductive agent solution with a solid content of 6 wt % and the first slurry obtained in step (1) by a third stirring process at a speed of 28 rpm for 15 min, vacuum stirring at a speed of 15 rpm and vacuum dispersion at a speed of 650 rpm were simultaneously performed at a vacuum degree of -0.085 MPa for 4.5 h to obtain a muddy second slurry with a solid content of 72 wt %, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry was 93:6:2.5:4;

(3) After mixing the aqueous adhesive solution and water obtained in step (2) with the second slurry obtained in step (2) by a fourth stirring process at a speed of 15 rpm for 30 min, vacuum stirring at a speed of 20 rpm and vacuum dispersion at a speed of 2800 rpm were simultaneously performed at a vacuum degree of -0.096 MPa for 1.5 h to obtain a lithium ion battery positive electrode slurry with a solid content of 60 wt%. The mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry was 93:6:4.8:4.

Example 4

This embodiment provides an aqueous homogenization process for a lithium-ion battery positive electrode system, and the aqueous homogenization process comprises the following steps:

(1) mixing the positive electrode main material and the conductive agent by a first stirring process at a rotation speed of 30 rpm for 10 min to obtain a mixed powder, and then infiltrating the mixed powder with water by a second stirring process at a rotation speed of 24 rpm for 20 min to obtain a muddy first slurry with a solid content of 80 wt %, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry is 90:10;

(2) After mixing the aqueous adhesive solution with a solid content of 20 wt %, the aqueous conductive agent solution with a solid content of 5 wt % and the first slurry obtained in step (1) by a third stirring process at a rotation speed of 30 rpm for 10 min, vacuum stirring at a rotation speed of 28 rpm and vacuum dispersion at a rotation speed of 800 rpm were simultaneously performed for 3 h at a vacuum degree of -0.092 MPa to obtain a muddy second slurry with a solid content of 77 wt %, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry is 90:10:1.2:7;

(3) After mixing the aqueous adhesive solution and water obtained in step (2) with the second slurry obtained in step (2) by a fourth stirring process at a speed of 28 rpm for 13 min, vacuum stirring at a speed of 15 rpm and vacuum dispersion at a speed of 3000 rpm were simultaneously performed at a vacuum degree of -0.085 MPa for 1 h to obtain a lithium ion battery positive electrode slurry with a solid content of 50 wt%. The mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry was 90:10:4.2:7.

Example 5

This embodiment provides an aqueous homogenization process for a lithium-ion battery positive electrode system, and the aqueous homogenization process comprises the following steps:

(1) mixing the positive electrode main material and the conductive agent by a first stirring process at a speed of 15 rpm for 30 min to obtain a mixed powder, and then infiltrating the mixed powder with water by a second stirring process at a speed of 30 rpm for 10 min to obtain a muddy first slurry with a solid content of 85 wt %, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry is 99:0.5;

(2) After mixing the aqueous adhesive solution with a solid content of 15 wt %, the aqueous conductive agent solution with a solid content of 10 wt % and the first slurry obtained in step (1) by a third stirring process at a rotation speed of 15 rpm for 30 min, vacuum stirring at a rotation speed of 30 rpm and vacuum dispersion at a rotation speed of 500 rpm were simultaneously performed at a vacuum degree of -0.1 MPa for 5 h to obtain a muddy second slurry with a solid content of 70 wt %, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry is 99:2:1.2:3;

(3) After mixing the aqueous adhesive solution and water obtained in step (2) with the second slurry obtained in step (2) by a fourth stirring process at a speed of 30 rpm for 10 min, vacuum stirring at a speed of 30 rpm and vacuum dispersion at a speed of 2500 rpm were simultaneously performed for 3 h at a vacuum degree of -0.088 MPa to obtain a lithium ion battery positive electrode slurry with a solid content of 56 wt%. The mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry was 99:2:4:3.

Example 6

This embodiment provides an aqueous slurrying process for a lithium-ion battery positive electrode system. Except that the solid content of the first slurry in step (1) is 76 wt %, the rest is the same as that of embodiment 1.

Example 7

This embodiment provides an aqueous slurry process for a lithium-ion battery positive electrode system, which is the same as that of Embodiment 1 except that the solid content of the first slurry in step (1) is 90 wt %.

Example 8

This embodiment provides an aqueous slurrying process for a lithium-ion battery positive electrode system, which is the same as that of Embodiment 1 except that the solid content of the second slurry in step (2) is 65 wt %.

Example 9

This embodiment provides an aqueous slurry process for a lithium-ion battery positive electrode system, which is the same as that of Embodiment 1 except that the solid content of the second slurry in step (2) is 80 wt %.

Example 10

This embodiment provides an aqueous slurry process for a lithium-ion battery positive electrode system, which is the same as that of Embodiment 1 except that the solid content of the aqueous adhesive solution in step (2) is 12 wt %.

Embodiment 11

This embodiment provides an aqueous slurry process for a lithium-ion battery positive electrode system, which is the same as that of Embodiment 1 except that the solid content of the aqueous adhesive solution in step (2) is 25 wt %.

Example 12

This embodiment provides an aqueous slurry process for a lithium-ion battery positive electrode system, which is the same as that of Embodiment 1 except that the solid content of the aqueous conductive agent gel solution in step (2) is 3 wt %.

Example 13

This embodiment provides an aqueous slurry process for a lithium-ion battery positive electrode system, which is the same as that of Embodiment 1 except that the solid content of the aqueous conductive agent gel solution in step (2) is 15 wt %.

The fineness and viscosity of the positive electrode slurry of the lithium ion battery obtained in the above embodiment were tested, and the test results are shown in Table 1;

The test method for the fineness of the positive electrode slurry of lithium-ion batteries is to scrape the fineness plate;

The viscosity of the positive electrode slurry of the lithium-ion battery is tested by using a viscometer;

A lithium-ion battery was prepared using the lithium-ion battery positive electrode slurry obtained in the above embodiment. The preparation method was: coating the slurry on a foil and drying it, and performing a battery capacity test and a stability test on the prepared lithium-ion battery by lamination. The test results are shown in Table 1. The test method was 1000 cycles at 0.5C.

Table 1

	Fineness (μm)	Viscosity (cp)	Battery capacity (mAh/g)	Capacity retention rate (%)
Example 1	15	5000	138.2	96
Example 2	10	5500	136.5	96.5
Example 3	10	6000	133.5	99
Example 4	10	8000	130.4	99.3
Example 5	20	4000	139.4	96
Example 6	28	Unstable	112.9	84
Example 7	27	Unstable	115.3	86
Example 8	25	6200	118.5	88
Example 9	28	Unstable	114.6	85
Example 10	26	Unstable	119.4	88
Embodiment 11	27	Unstable	113.8	87
Example 12	twenty four	Unstable	121.2	89
Example 13	26	Unstable	117.5	84

From Table 1, we can get:

(1) The positive electrode slurry of the lithium ion battery prepared in Examples 1 to 5 has low fineness and high uniformity, and the prepared lithium ion battery has high capacity and capacity retention rate; in the aqueous slurry process of the positive electrode system of the lithium ion battery described in the present application, the positive electrode main material and the conductive agent are mixed in step (1), and then a small amount of water is added to wet it first, thereby avoiding the agglomeration of the mixed powder; in step (2), the aqueous adhesive glue, the aqueous conductive agent glue and the first slurry are mixed by scraping, stirring and dispersing at an appropriate solid content, The solid content will not reach the kneading state, thus avoiding the agitator from scratching the cylinder wall and sticking to the cylinder during the kneading process, thereby avoiding the slurry sticking to the cylinder from being squeezed and rubbed in time, resulting in poor dispersion effect of the final lithium-ion battery positive electrode slurry; in step (2), the water-based adhesive glue, the water-based conductive agent glue and the first slurry are evenly dispersed through a one-step glue adding process, which effectively reduces the investment cost of the slurry preparation process, shortens the time of the water-based homogenization process, improves the overall process efficiency, and effectively ensures the stability and uniformity of the water-based positive electrode system slurry;

(2) By comparing Example 1 with Examples 6 and 7, it can be seen that the solid content of the first slurry in the present application will affect the viscosity and fineness of the prepared lithium-ion battery positive electrode slurry, and will also affect the capacity and stability of the lithium-ion battery prepared with the lithium-ion battery positive electrode slurry; when the solid content of the wetted mixed powder is low, that is, there is too much water, the viscosity of the lithium-ion battery positive electrode slurry will be unstable, the fineness will increase, the battery capacity of the lithium-ion battery will decrease, and the capacity retention rate will decrease. This is because the volume of the unwetted powder is large, and adding water to wet it can reduce the volume of the powder. If the water content of the wetted powder is excessive, part of the powder will agglomerate into larger particles. These over-wetted large particles will agglomerate into larger particles during stirring. On the rod or cylinder wall, these large particles may enter the slurry in the subsequent homogenization, resulting in large fineness of the final slurry, large slurry particles, poor performance of the prepared battery capacity, and rapid capacity decay; when the solid content of the first slurry is too high, the viscosity of the positive electrode slurry of the lithium-ion battery will be unstable, the fineness will increase, the battery capacity of the lithium-ion battery will be reduced, and the capacity retention rate will be reduced. This is because when the wetting liquid is less, the powder is not fully wetted, the powder volume is still large, and it will still agglomerate when the glue and conductive agent are added for the second time, and part of the slurry cannot be dispersed on the rod, resulting in poor slurry dispersion effect, poor performance of the prepared battery capacity, and rapid capacity decay;

(3) By comparing Example 1 with Examples 8 and 9, it can be seen that the solid content of the second slurry in the present application will affect the viscosity and fineness of the prepared positive electrode slurry for lithium-ion batteries, and will also affect the capacity and stability of lithium-ion batteries prepared with the positive electrode slurry for lithium-ion batteries; when the solid content of the second slurry is low, the viscosity and fineness of the positive electrode slurry for lithium-ion batteries will increase, the battery capacity of the lithium-ion batteries will decrease, and the capacity retention rate will decrease. This is because the slurry viscosity is too low, the friction between the slurry particles is small, and the dispersion disk cannot disperse the agglomerated particles; when the solid content of the second slurry is high, the viscosity of the positive electrode slurry for lithium-ion batteries will be unstable, the fineness will increase, the battery capacity of the lithium-ion batteries will decrease, and the capacity retention rate will decrease. This is because when the slurry viscosity is high, there will be phenomena such as slurry mud climbing the rod and sticking to the wall. These slurries on the rod and the cylinder wall cannot be dispersed, which will result in poor slurry dispersion effect, poor performance of the prepared battery capacity, and rapid capacity decay;

(4) By comparing Example 1 with Examples 10 and 11, it can be seen that the solid content of the aqueous adhesive solution in step (2) of the present application will affect the viscosity and fineness of the prepared lithium-ion battery positive electrode slurry, and will also affect the capacity and stability of the lithium-ion battery prepared with the lithium-ion battery positive electrode slurry; when the solid content of the aqueous adhesive solution is low, the viscosity of the lithium-ion battery positive electrode slurry will be unstable, the fineness will increase, the battery capacity of the lithium-ion battery will decrease, and the capacity retention rate will decrease. This is because the solution with a low solid content contains a large amount of water. Adding part of the solution can achieve the target solid content, but the first and second slurries are The binder content in the slurry may be too little, resulting in poor dispersion effect; when the solid content of the aqueous adhesive solution is too high, the viscosity of the positive electrode slurry of the lithium-ion battery will be unstable, and the battery capacity and capacity retention rate of the lithium-ion battery will be inconsistent. This is because the high solid content of the slurry has high viscosity, less water, strong cohesion, relatively poor fluidity, and is not easy to penetrate, which will cause some particles in the slurry to be coated with a large amount of binder, and some particles to be coated with less binder. The particles coated with less binder are easy to agglomerate, resulting in poor slurry stability, which may cause unstable surface density during coating, and the prepared battery has poor electrical performance consistency;

(5) By comparing Example 1 with Examples 12 and 13, it can be seen that the solid content of the aqueous conductive agent slurry in step (2) of the present application will affect the viscosity and fineness of the prepared lithium ion battery positive electrode slurry, and will also affect the capacity and stability of the lithium ion battery prepared with the lithium ion battery positive electrode slurry; when the solid content of the aqueous conductive agent slurry is low, the viscosity of the lithium ion battery positive electrode slurry will be unstable and the fineness will increase, the battery capacity of the lithium ion battery will be reduced and the consistency will be poor, and the capacity retention rate will be reduced. This is because there is more solvent water in the low-solid aqueous slurry. When a certain proportion of the conductive agent is added to the slurry, it is necessary to reduce the amount of the slurry. The amount of conductive agent should be less, the dispersion effect is poor, the slurry is unstable, the surface density is unstable during coating, and the battery performance is poor. When the solid content of the aqueous conductive agent glue is too high, the viscosity of the positive electrode slurry of the lithium-ion battery will be unstable and the fineness will increase. The battery capacity of the lithium-ion battery will be reduced, the consistency will be poor, and the capacity retention rate will be reduced. This is because the viscosity of the high-solid content conductive agent is relatively high and the fluidity is poor. The conductive agent will regroup and cannot be evenly attached to the main materials. Some main materials will have more conductive agent and some places will have less, resulting in poor conductivity.

In summary, the lithium-ion battery positive electrode slurry prepared by the aqueous homogenization process of the lithium-ion battery positive electrode system described in the present application has lower particle size and higher stability. The aqueous homogenization process is short in time, has higher preparation efficiency, lower preparation cost and lower requirements on the production environment and production equipment.

Claims (20)

1. A water system homogenization process for a lithium ion battery positive electrode system, the water system homogenization process comprising the following steps:

   (1) mixing a positive electrode main material and a conductive agent to obtain a mixed powder, and soaking the mixed powder with water to obtain a wet first slurry;

   (2) mixing the aqueous adhesive solution, the aqueous conductive agent solution and the first slurry obtained in step (1), and simultaneously performing vacuum stirring and vacuum dispersion to obtain a muddy second slurry;

   (3) After mixing the aqueous adhesive solution, water and the second slurry obtained in step (2), vacuum stirring and vacuum dispersion are simultaneously performed to obtain a positive electrode slurry for a lithium-ion battery.
2. The aqueous homogenization process according to claim 1, wherein the mixing method in step (1) includes a first stirring; the rotation speed of the first stirring is 15-30 rpm, and the time is 10-30 min.
3. The aqueous homogenization process according to claim 1 or 2, wherein the wetting method in step (1) includes a second stirring; the rotation speed of the second stirring is 15-30 rpm, and the time is 10-30 min.
4. The aqueous homogenization process according to any one of claims 1 to 3, wherein the positive electrode main material in step (1) comprises any one of a ternary positive electrode material, lithium iron phosphate, elemental sulfur or lithium manganese oxide, or a combination of at least two thereof.
5. The aqueous homogenization process according to any one of claims 1 to 4, wherein the conductive agent in step (1) comprises any one of conductive carbon black, conductive graphite, acetylene black or Ketjen black, or a combination of at least two thereof.
6. The aqueous homogenization process according to any one of claims 1 to 5, wherein the solid content of the first slurry in step (1) is 80 to 85 wt%.
7. The aqueous homogenization process according to any one of claims 1 to 6, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry in step (1) is (90-99):(0.5-10).
8. The water system homogenization process according to any one of claims 1 to 7, wherein the mixing method in step (2) includes a third stirring; the rotation speed of the third stirring is 15 to 30 rpm, and the time is 10 to 30 min;

   The rotation speed of the vacuum stirring in step (2) is 15-30 rpm; the rotation speed of the vacuum dispersion in step (2) is 500-800 rpm; the vacuum degree of the vacuum stirring and vacuum dispersion in step (2) is -0.1-0.085 MPa; the time of the vacuum stirring and vacuum dispersion in step (2) is 3-5 h.
9. The water-based homogenization process according to any one of claims 1 to 8, wherein the water-based adhesive solution in step (2) comprises a water-based adhesive and water, and the water-based adhesive comprises any one of polyvinylidene fluoride adhesive, styrene-butadiene rubber latex adhesive, carboxymethyl cellulose adhesive, polyacrylic acid adhesive, polyacrylonitrile adhesive or polyacrylate adhesive, or a combination of at least two thereof.
10. The water-based homogenization process according to any one of claims 1 to 9, wherein the solid content of the water-based adhesive solution in step (2) is 15 to 20 wt%.
11. The aqueous homogenization process according to any one of claims 1 to 10, wherein the aqueous conductive agent slurry in step (2) comprises an aqueous conductive agent and water, and the aqueous conductive agent comprises any one of carbon nanofibers, carbon nanotubes or graphene, or a combination of at least two of them.
12. The aqueous slurry process according to any one of claims 1 to 11, wherein the solid content of the aqueous conductive agent slurry in step (2) is 5 to 10 wt%.
13. The aqueous homogenization process according to any one of claims 1 to 12, wherein the solid content of the second slurry in step (2) is 70 to 77 wt%.
14. The aqueous slurry process according to any one of claims 1 to 13, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry of step (2) is (90~99):(0.5~10):(1~3):(0.5~10).
15. The water system homogenization process according to any one of claims 1 to 14, wherein the mixing method in step (3) includes a fourth stirring; the rotation speed of the fourth stirring is 15 to 30 rpm, and the time is 10 to 30 min;

    The rotation speed of the vacuum stirring in step (3) is 15-30 rpm; the rotation speed of the vacuum dispersion in step (3) is 2500-3000 rpm; the vacuum degree of the vacuum stirring and vacuum dispersion in step (3) is -0.1-0.085 MPa; the time of the vacuum stirring and vacuum dispersion in step (3) is 1-3 h.
16. The water-based homogenization process according to any one of claims 1 to 15, wherein the water-based adhesive solution in step (3) is the same as the water-based adhesive solution in step (2).
17. The aqueous homogenization process according to any one of claims 1 to 16, wherein the solid content of the lithium-ion battery positive electrode slurry in step (3) is 50 to 60 wt%;

    The viscosity of the lithium-ion battery positive electrode slurry in step (3) is 4000-8000cp;

    The fineness of the lithium-ion battery positive electrode slurry in step (3) is 10-20 μm;

    The mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry in step (3) is (90-99):(0.5-10):(3-10):(0.5-10).
18. The aqueous homogenization process according to any one of claims 1 to 17, wherein the aqueous homogenization process comprises the following steps:

    (1) mixing the positive electrode main material and the conductive agent by a first stirring process at a rotation speed of 15 to 30 rpm for 10 to 30 min to obtain a mixed powder, and then infiltrating the mixed powder with water by a second stirring process at a rotation speed of 15 to 30 rpm for 10 to 30 min to obtain a first slurry with a wet solid content of 80 to 85 wt %, wherein the mass ratio of the positive electrode main material to the conductive agent in the first slurry is (90 to 99):(0.5 to 10);

    (2) After mixing the aqueous adhesive solution with a solid content of 15-20wt%, the aqueous conductive agent solution with a solid content of 5-10wt% and the first slurry obtained in step (1) by a third stirring process at a rotation speed of 15-30rpm for 10-30min, vacuum stirring at a rotation speed of 15-30rpm and vacuum dispersion at a rotation speed of 500-800rpm for 3-5h at a vacuum degree of -0.1-0.085Mpa are simultaneously performed to obtain a muddy second slurry with a solid content of 70-77wt%, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the second slurry is (90-99):(0.5-10):(1-3):(0.5-10);

    (3) After mixing the aqueous adhesive solution and water obtained in step (2) by a fourth stirring process at a speed of 15-30 rpm for 10-30 min, vacuum stirring at a speed of 15-30 rpm and vacuum dispersion at a speed of 2500-3000 rpm for 1-3 h are simultaneously performed at a vacuum degree of -0.1-0.085 MPa to obtain a lithium ion battery positive electrode slurry with a solid content of 50-60 wt %, a viscosity of 4000-8000 cp and a fineness of 10-20 μm, wherein the mass ratio of the positive electrode main material, the conductive agent, the aqueous adhesive and the aqueous conductive agent in the lithium ion battery positive electrode slurry is (90-99):(0.5-10):(3-10):(0.5-10).
19. A positive electrode slurry for a lithium-ion battery, wherein the positive electrode slurry for a lithium-ion battery is prepared by the aqueous homogenization process according to any one of claims 1 to 18.
20. A lithium ion battery, comprising the lithium ion battery positive electrode slurry according to claim 19.