Setting Up a 20L Vacuum Planetary Mixer for Lithium Battery Slurry Production

Establishing a reliable process for lithium battery slurry production requires careful consideration of equipment selection, process parameters, and operational procedures. This guide outlines the key steps for utilizing the 20L Vacuum Planetary Mixer (SXJ-20 model) for high-quality cathode and anode slurry preparation in R&D and pilot-scale production.

Step 1: Material Preparation and Formulation

The first step in successful battery slurry production is proper material preparation. Lithium battery formulations typically include active materials (cathode: LiCoO2, LiFePO4, NMC, NCA; anode: graphite, silicon-carbon composites), conductive carbon black (Super P, CNT), binders (PVDF, SBR, CMC), and solvents (NMP, deionized water) . All materials should be accurately weighed and dried to remove moisture that could affect slurry quality. For PVDF binders, pre-dissolution in NMP is recommended to ensure uniform distribution during mixing.

Step 2: Planetary Mixing and Dispersion

The 20L Vacuum Planetary Mixer's combination of low-speed kneading and high-speed dispersion is ideal for battery slurry preparation. The standard process involves:

1. Initial charging: Add binder solution and solvents to the mixing vessel

2. Powder addition: Introduce active materials and conductive additives under vacuum

3. Low-speed mixing: Operate the planetary blades at 20-42 rpm for initial incorporation

4. High-speed dispersion: Activate the 3KW disperser at 1,500-2,980 rpm for 30-120 minutes

5. Final mixing: Continue low-speed mixing under vacuum for deaeration

The PTFE scraper ensures continuous wall cleaning, preventing material buildup that could affect heat transfer and mixing uniformity . The entire process should be performed under -0.09 MPa vacuum to remove entrapped air and prevent oxidation.

Step 3: Process Optimization and Quality Control

Achieving consistent slurry quality requires careful parameter control. The 20L Vacuum Planetary Mixer's parameters should be optimized for each formulation:

Quality control should include viscosity measurements (using a rheometer), particle size analysis, solid content testing, and visual inspection for agglomerates and bubbles. The 20L capacity allows for multiple test samples, enabling comprehensive characterization without excessive material consumption .

Step 4: Discharge and Downstream Processing

After mixing, the slurry must be discharged for coating. The 20L Vacuum Planetary Mixer offers two discharge options:

1. Direct discharge: Remove the mixing vessel and transfer slurry manually

2. Optional presser: Use the extrusion system for controlled, contamination-free discharge

The presser attachment is particularly valuable for high-viscosity slurries, as it applies uniform pressure to extrude the material without introducing air bubbles . The discharged slurry should be transferred to a coating machine within 4-8 hours to prevent settling or gelation.

Step 5: Cleaning and Maintenance

Proper cleaning is essential for maintaining the 20L Vacuum Planetary Mixer's performance. The electric lifting system provides easy access to the mixing vessel, disperser, and blades . For NMP-based slurries, cleaning should include:

1. Solvent rinse: Use NMP or appropriate solvent to dissolve residual slurry

2. Mechanical cleaning: Scrape and wipe all contact surfaces

3. Inspection: Check PTFE scraper wear and blade clearances

4. Seal maintenance: Verify mechanical seal integrity for vacuum performance