Positive Electrode Formulation Process
(Composition: Active Material, Conductive Agent, Binder)

1. Raw Material Confirmation & Drying:

   • Conductive agent: ~120°C for 8 hours.

   • Binder (PVDF): ~80°C for 8 hours.

   • Active material (LFP, NCM, etc.): Drying requirement depends on incoming material condition and specific process.

   • Current Workshop Requirements: Temperature ≤40°C, Humidity ≤25% RH.

2. PVDF Solution Preparation (Wet Mixing Process):

   • Prepare PVDF solution (Solute: PVDF, Solvent: NMP) in advance. Solution quality critically impacts battery internal resistance and electrical performance.

   • Key Influencing Factors:

     • Temperature: Higher temperatures cause yellowing, reducing adhesive properties.

     • Agitation Speed: Excessive speed damages the solution. Optimal speed depends on disperser disc size, typically targeting a disc linear speed of 10-15 m/s (highly equipment-dependent).

   • Process Requirements: Circulating cooling water must be active. Temperature ≤30°C.

3. Positive Electrode Slurry Mixing:

   • Strictly follow procedures for addition sequence (Active Material + Conductive Agent mixed first under slow stirring, then PVDF solution added), addition timing, and ratios.

   • Precisely control equipment revolution/rotation speed (Dispersing linear speed generally ≥17 m/s, varies significantly by equipment manufacturer), vacuum level, and temperature.

   • Regularly test slurry particle size (fineness) and viscosity. These properties are closely tied to solid content, material characteristics, addition sequence, and process parameters (detailed discussion not included here).

   • Process Requirements: Temperature ≤30°C, Humidity ≤25% RH, Vacuum ≤ -0.085 MPa.

4. Slurry Transfer & Screening:

   • Transfer slurry to holding tanks or the coating department.

   • Screen slurry during transfer to remove large particles, sediment, and ferromagnetic impurities.

     • Large particles risk coating defects, leading to excessive self-discharge or short circuits.

     • High ferromagnetic content causes excessive self-discharge.

   • Process Requirements: Temperature ≤40°C, Humidity ≤25% RH, Screen mesh ≤100 mesh, Target Particle Size ≤15µm (Parameters for reference).

Negative Electrode Formulation Process
(Composition: Active Material, Conductive Agent, Binder, Dispersant)

1. Raw Material Confirmation & Environment:

   • Conventional negative electrode systems use an aqueous mixing process (solvent: deionized water - DI water). Thus, raw material drying is typically unnecessary.

   • Key Requirement: DI Water Conductivity ≤1 µS/cm.

   • Workshop Requirements: Temperature ≤40°C, Humidity ≤25% RH.

2. Slurry Mixing Process:

   1. Prepare Binder Solution: Make CMC solution in DI water.

   2. Dry Mixing: Load Graphite (C) and Conductive Agent into mixer.

      • Mix dry. Vacuum not recommended.

      • Activate circulating cooling water (critical due to heat generation from particle friction).

      • Low Speed: 15-20 rpm.

      • Scrape down sides and bottom every ~15 minutes; repeat 2-3 cycles.

   3. Wet Mixing (CMC Solution Addition):

      • Add CMC solution to the dry mix.

      • Engage vacuum (≤ -0.09 MPa).

      • Low Speed (15-20 rpm): Run for 2 scrape-down cycles.

      • Adjust Speeds: Low Speed (~35 rpm) + High Speed (1200-1500 rpm).

      • Mixing Time: 15-60 minutes (highly process/manufacturer dependent).

   4. SBR Latex Addition:

      • Add SBR latex.

      • Mix quickly with minimal time at appropriate speeds (SBR is a long-chain polymer; excessive speed/time breaks chains, deactivating it).

      • Recommended: Low Speed (35-40 rpm) + High Speed (1200-1800 rpm) for 10-20 minutes.

3. Final Slurry QC & Transfer Prep:

   • Test final slurry properties:

     • Viscosity: 2000-4000 mPa·s

     • Particle Size (Dv100): ≤35µm

     • Solid Content: 40-70%
       (Note: Target values vary based on material properties and mixing process).

   • De-gas (vacuum) and screen slurry (≤100 mesh).

   • Workshop Requirements: Temperature ≤30°C, Humidity ≤25% RH.