How to Reduce Irregular Graphite Anode Particles to Near‑Spherical Prototypes

Natural flake graphite and mechanically crushed artificial graphite inherently form irregular, flaky, angular particles. These irregular shapes bring low tap density, poor particle packing, high specific surface area, increased electrolyte side reactions and unstable cycling performance in lithium‑ion batteries. Conventional crushing only breaks large particles into smaller irregular fragments and cannot reshape morphology. Converting irregular graphite into near‑spherical prototypes relies on controlled particle‑to‑particle collision, friction and shear forces, without excessive pulverization. JACAN integrated grinding and spheroidization systems are designed for this exact morphology transformation from irregular raw powder to near‑spherical graphite anode prototypes.

Core Principle of Graphite Spheroidization

The goal is not to melt or chemically modify graphite crystal structure, but mechanical reshaping:
High‑speed circulating rotor drives graphite particles to collide and rub against each other repeatedly. Sharp corners, flaky protrusions and irregular edges are gradually worn away. The main particle body remains intact. After multiple circulation passes, irregular flakes and angular pieces evolve into compact, near‑spherical prototypes with improved sphericity and tap density.
Key control targets for prototypes:

• Sphericity: ≥0.82–0.88
• D50: 10–30 μm (adjustable for different anode grades)
• Tap density: ≥1.05 g/cm³
• Low fine particle generation during reshaping

Step‑by‑Step Process to Produce Near‑Spherical Graphite Anode Prototypes

1. Raw Material Preparation and Pre‑Grinding

Raw irregular graphite feedstock usually has large flake sizes and broad particle distribution.

1. Control moisture below 0.5% to prevent powder agglomeration during high‑speed circulation.
2. Pre‑crush large flakes using air classifier mill to narrow PSD, remove oversized chunks.
3. Remove ferromagnetic impurities via magnetic separation before spheroidization, avoiding metal contamination of anode materials.
   At this stage, particles are still irregular; this step only prepares suitable feed size for subsequent reshaping.

2. Circulating Spheroidization Shaping (Core Stage)

The pre‑sized irregular graphite enters the JACAN spheroidization unit.

• Rotor creates high‑speed turbulent flow inside the shaping chamber.
• Particles circulate repeatedly, generating mutual friction and low‑energy impact.
• Flaky edges and irregular bulges are abraded and rounded off.
• Internal dynamic classifier continuously extracts over‑fine powders generated by edge abrasion to stop fines accumulation.
  Process parameters to tune for prototype quality: rotor speed, feed rate, circulation cycles, airflow volume.
  Higher speed improves sphericity but increases fines yield; lower speed reduces over‑grinding yet leaves residual irregular features.

3. Air Classification for Particle Size Sorting

After spheroidization, powder mixture contains near‑spherical prototypes, residual irregular coarse particles and ultrafine debris.
Multi‑stage air classification separates three fractions:

1. Oversized irregular particles: return back to spheroidizer for re‑shaping.
2. Target near‑spherical prototypes: collected as intermediate product.
3. Ultrafine powder byproduct: separated out to avoid raising specific surface area.
   Closed loop circulation ensures maximum yield of qualified near‑spherical prototypes.

4. Post Purification and Quality Inspection

1. Secondary magnetic separation again removes metal impurities from equipment wear.
2. Test particle morphology, PSD, tap density, sphericity and BET to verify prototype quality.
3. Qualified near‑spherical graphite prototypes can go to carbon coating and high‑temperature graphitization for finished anode material.

Equipment Selection Guidelines

Traditional ball mills, hammer mills only break particles, cannot reshape flakes into spheres.
Recommended configuration: Integrated air classifier mill + circulating spheroidization system.

• Shaping chamber with anti‑wear ceramic lining to reduce metal contamination.
• Dynamic classifier with adjustable speed to precisely control particle cut point.
• Closed inert gas optional for ultra‑pure graphite processing to prevent oxidation.

Typical Process Challenges & Solutions

1. Poor sphericity after shaping
   Cause: Insufficient circulation time or uneven particle size of feed.
   Solution: Narrow raw PSD in pre‑grinding stage, increase circulation passes.
2. Too many ultrafine particles and low tap density
   Cause: Over‑high rotor speed, excessive impact force.
   Solution: Reduce rotor speed, optimize airflow to separate fines timely.
3. Powder agglomeration during shaping
   Cause: High raw material moisture.
   Solution: Dry feedstock before feeding into spheroidizer.

Turning irregular graphite anode particles into near‑spherical prototypes depends on mechanical spheroidization rather than simple crushing. The complete workflow includes raw material pre‑grinding and impurity removal, circulating friction/impact reshaping, closed‑loop classification and post purification. By tuning rotor speed, circulation cycles and airflow parameters, flaky and angular graphite particles lose irregular edges and become compact near‑spherical prototypes. This morphology upgrade improves tap density and electrochemical performance, laying a solid foundation for high‑performance lithium‑ion battery anode materials.