Common methods and precautions for improving the mixing uniformity of lithium-ion battery slurry

Abstract:In this paper, the common methods for improving the stirring uniformity of lithium-ion battery slurry are elaborated in detail, including planetary stirring method, vacuum stirring method, multi-stage stirring method, high-speed dispersion method, constant temperature stirring method and optimization stirring parameters, and the matters that need to be paid attention to in the practical application of these methods are analyzed, aiming to provide theoretical support and practical reference for optimizing the production process of lithium-ion batteries and improving battery performance.

I. Introduction

As a widely used energy storage device, the performance and quality of lithium-ion batteries largely depend on the uniformity of the slurry. As a key link in the battery manufacturing process, stirring directly affects the dispersion state and distribution uniformity of active substances, conductive agents, binders and other components in the slurry. It is of great practical significance to study how to improve the stirring uniformity of lithium-ion batteries.

2. A common method to improve the mixing uniformity of lithium-ion battery slurry

(1) Planetary stirring method

1. Principle: The planetary stirring method uses the principle of planetary motion to make the stirring paddle rotate while revolutionizing, so as to realize the all-round stirring of the material.

2. Advantages: It can handle high viscosity slurry, and the mixing effect is uniform, which can effectively avoid the deposition and delamination of materials.

3. Key points of operation: By reasonably adjusting the rotation speed, rotation line speed and mixing time, to ensure that the materials in different positions can be fully stirred.

(2) Vacuum stirring method

1. Principle: Stirring in a vacuum environment can reduce the bubble content in the slurry and make the components more tightly combined.

2. Advantages: It helps to reduce defects inside the battery and improve the cycle performance and consistency of the battery.

3. Key points of operation: control the size of the vacuum degree and the time of vacuuming, and avoid introducing new gas during the stirring process.

(3) Multi-stage stirring method

1. Principle: Adopt multi-stage stirring method to gradually enhance the stirring intensity and prolong the stirring time.

2. Advantages: The uniformity of the slurry is gradually improved, and the risk of uneven mixing is reduced.

3. Key points of operation: Reasonably design the parameters of mixing at all levels, such as speed, time, etc., to ensure that each stage of mixing can achieve the expected effect and achieve a smooth transition between all levels.

(4) High-speed dispersion method

1. Principle: The high-speed rotating dispersion disc or dispersion shaft is used to generate strong shear force and centrifugal force to break the agglomerate of the material.

2. Advantages: It can quickly disperse the particles evenly and improve the mixing efficiency.

3. Key points of operation: pay attention to control the time and speed of high-speed dispersion to avoid particle crushing or performance degradation caused by excessive dispersion.

(5) Constant temperature stirring method

1. Principle: Stirring is carried out under specific constant temperature conditions to control the viscosity and fluidity of the slurry.

2. Advantages: It helps to maintain the stability of the slurry, reduce viscosity fluctuations and phase separation caused by temperature changes.

3. Key points of operation: Accurately control the stirring temperature, choose the appropriate heating or cooling method, and ensure that the temperature is evenly distributed.

(6) Optimize mixing parameters

1. Stirring speed

According to the nature and formula of the slurry, choose the appropriate mixing speed. Too low a speed will not disperse the material effectively, and too high a speed may cause the slurry to splash and overheat.

2. Stirring temperature

Temperature has a significant effect on the viscosity and fluidity of the slurry. Different raw materials may exhibit different compatibility at specific temperatures, and the optimal stirring temperature range needs to be determined experimentally.

3. Vacuum

The degree of vacuum is directly related to the removal effect of air bubbles. However, too high a vacuum degree may cause the solvent to evaporate too quickly, affecting the solids content and properties of the slurry.

3. Precautions

(1) The influence of material properties

Different active substances, conductive agents and binders have different physicochemical properties, such as particle size distribution, specific gravity, wettability, etc. These characteristics need to be fully considered when selecting mixing methods and parameters in order to achieve the best mixing results.

For example, for active substances with small particle size and easy to agglomerate, it may be necessary to use high-speed dispersion or increase the stirring time to improve the dispersion effect.

(2) Equipment selection and maintenance

Suitable mixing equipment is the basis for ensuring the uniformity of mixing. Appropriate models and specifications of mixing equipment should be selected according to the production scale, slurry characteristics and process requirements.

At the same time, the mixing equipment should be maintained and maintained regularly to ensure that it is in good operating condition, such as the wear and tear of the mixing paddle, sealing performance, etc., so as to avoid the impact of equipment failure on the mixing effect.

(3) Stirring sequence

When adding raw materials, a proper mixing sequence is essential to improve uniformity. In general, solvents should be added first, followed by binders, conductive agents, and active substances to ensure that the components can be fully dissolved and dispersed.

(4) Verification and optimization of mixing process

Before actual production, sufficient experiments and tests are required to verify the feasibility and effectiveness of the selected mixing process. By detecting the particle size distribution, viscosity, solid content and other indicators of the slurry after stirring, the mixing uniformity is evaluated, and the process is optimized and adjusted according to the results.

(5) Environmental control

The stirring process should be carried out in a clean, dry, constant temperature and humidity environment to avoid the influence of external factors on the performance of the slurry. Dust, humidity, etc. can cause slurry contamination or change in properties.

(6) Personnel operation specifications

The operator should be familiar with the operating procedures and precautions of the mixing equipment, and operate in strict accordance with the process requirements to ensure the stability and consistency of the mixing process.

IV. Conclusions

Improving the mixing uniformity of lithium-ion battery slurry is a comprehensive problem, which needs to comprehensively consider the selection of mixing method, optimization of mixing parameters, matching of material characteristics, equipment and environment. By rationally using common methods such as planetary stirring, vacuum stirring, and multi-stage stirring, and paying attention to relevant precautions, the uniformity and stability of lithium-ion battery slurry can be significantly improved, so as to lay a solid foundation for improving the performance and quality of lithium-ion batteries. With the continuous progress of technology and in-depth research, more advanced and efficient stirring technology will emerge in the future to further promote the development of the lithium-ion battery industry.

Article source: lithium battery technology knowledge platform

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