Date: 2025-01-07 hits: 157
1. Composition of lithium battery slurry
Lithium battery slurry is mainly composed of active materials (positive and negative electrode materials), conductive agents, binders, and solvents.
(1) Active substance
The positive electrode is lithium metal oxide, such as lithium cobalt oxide (LiCoOz), lithium iron phosphate (LiFePO4), ternary materials (LiNi1-x-yCoxMnyOz), etc; The negative electrode is made of graphite, silicon-based materials, etc.
（2）Conductive agent
Common conductive agents include carbon black, graphite, carbon fiber, carbon nanotubes, etc. Their function is to improve the conductivity of the electrode.
（3）Adhesive
Adhesives are used to bond active substances and conductive agents to current collectors. Common adhesives include polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), etc.
（4）Solvent
Solvent is used to dissolve binders, and common solvents include N-methylpyrrolidone (NMP) deionized water, etc.
2. Process flow of lithium battery slurry preparation
（1） Material pretreatment
Pre treatment such as drying and sieving of active substances, conductive agents, and binders to remove impurities and moisture, ensuring the purity and uniform particle size distribution of the materials.
(2) Slurry mixing
Add the active substance, conductive agent, binder, and solvent in a certain proportion into a stirring container for preliminary mixing. The mixing methods usually include mechanical stirring, magnetic stirring, and ultrasonic stirring.
（3） High-speed dispersion
On the basis of preliminary mixing, high-speed dispersing equipment (such as star dispersers, sand mills, etc.) is used to further disperse the slurry, in order to break down the aggregates and evenly disperse each component.
（4） Defoaming treatment
Bubbles will be introduced during the preparation of the slurry, affecting the coating quality, so defoaming treatment is required. The commonly used defoaming methods include vacuum defoaming, centrifugal defoaming, etc.
（5） Slurry filtration
By filtering and removing large particle impurities and agglomerates from the slurry, the fineness and uniformity of the slurry are ensured。
3. Key parameters for the preparation of lithium battery slurry
（1） Solid content
Solid content refers to the mass fraction of solid substances in the slurry. Appropriate solid content can ensure the coating performance of the slurry and the capacity of the battery. Generally speaking, the solid content of positive electrode slurry is between 50% -70%, and the solid content of negative electrode slurry is between 40% -60%.
（2） Viscosity
Viscosity is an important parameter for measuring the fluidity of slurry. Too high viscosity can lead to coating difficulties, while too low viscosity can affect the stability of the slurry and the consistency of coating thickness. Usually, the viscosity of the positive electrode slurry is between 4000-8000 mPa · s, and the viscosity of the negative electrode slurry is between 1000-5000 mPa's.
（3） Fineness
Fineness refers to the particle size of solid particles in the slurry. Smaller particle size helps improve battery performance, but excessive refinement can increase preparation costs. Generally, it is required that the particle size distribution of the slurry be within a certain range, such as D50 between 1-10 μ m. Slurry particle size test using a scraper fineness meter.
（4） PH value
For water-based slurries, the DH value will affect the stability of the binder and the surface chemical properties of the active substance. It is usually necessary to control the DH value of the slurry within a certain range to ensure the stability and performance of the slurry.
4. Factors affecting the preparation of lithium battery slurry
（1） Mixing speed and time
The mixing speed and time directly affect the uniformity and dispersion effect of the material. The mixing speed is too low or the time is too short, and the materials cannot be fully mixed and dispersed; Excessive stirring speed or time may damage the structure of the material, generate excessive heat, and even lead to the degradation of the binder.
(2） Temperature
Temperature also has a significant impact on the preparation process of the slurry. Higher temperatures can reduce the viscosity of the slurry and improve the dispersibility of the material, but excessively high temperatures may cause problems such as solvent evaporation and adhesive aging.
（3） Feeding sequence
The order of adding materials will affect the performance of the slurry., Generally speaking, adding solvents and binders first to fully dissolve and disperse them, and then adding active substances and conductive agents can achieve better results.
（4） Equipment selection
Different stirring, dispersing, and defoaming equipment have different performance and characteristics. Choosing the appropriate equipment is crucial to ensure the quality of slurry preparation.
5. Quality control of lithium battery slurry preparation
(1） Online detection
Real time monitoring of key parameters of the slurry is carried out using equipment such as online viscometers and particle size analyzers, and process parameters are adjusted in a timely manner to ensure the stability of slurry quality.
(2） Offline detection
Regularly sample the slurry, conduct offline viscosity, fineness, solid content and other tests, compare with standard values, and evaluate the quality of the slurry,
（3） Coating performance evaluation
By conducting actual coating experiments, observe the coating effect of the slurry, such as the uniformity of coating thickness, surface flatness, etc., and evaluate the coating performance of the slurry.
6. Conclusion
The preparation of lithium battery slurry is a complex and critical process that involves the comprehensive influence of multiple factors. By reasonably controlling the proportion of materials, optimizing the process flow and parameters, selecting appropriate equipment, and strengthening quality control, lithium battery slurries with excellent performance and high stability can be prepared, laying the foundation for improving the performance and consistency of lithium batteries.
