Can the Same Mill Be Used for Different Cathode Materials

The same grinding/classification mill hardware can be shared for multiple cathode materials (LFP, LMO, LCO, NCM, NCA), but it cannot run different materials interchangeably without strict process modification and thorough cleaning. Material properties differ greatly in thermal sensitivity, hardness, residual lithium, moisture tolerance and metal contamination requirements. This article is built on JACAN powder processing knowledge from ncm-mill.com.

1. Material property differences that impact shared use

• LFP & LMO: Good thermal stability, can use dry air; moderate hardness. Lower risk of thermal degradation.
• LCO: Moderate heat sensitivity; needs protection against surface lithium precipitation.
• NCM / NCA: Highly heat‑sensitive, prone to oxidation, re‑agglomeration and surface side reactions; must use closed-loop nitrogen inert atmosphere.

Hardness also varies: LCO is harder than LFP; single‑crystal NCM is harder than polycrystalline NCM. These differences change required grinding energy, feed rate and classifier settings.

2. Two levels of shared utilization

① Same mill, same material family (low risk)

Example: switching between different NCM grades (NCM523 / NCM622 / NCM811).

• Only adjust jet pressure, classifier speed, feed rate and gas dew point.
• Cleaning requirement is moderate.
• Still need inspection for residual powder buildup on classifier wheel, liner and filter.

② Same mill, cross-family cathode materials (high risk, strict changeover)

Example: Switch from LFP to NCA, or LMO to LCO.
This requires full material changeover protocol:

1. Complete mechanical cleaning: pulse back-blow, manual wipe of grinding chamber, classifier, cyclone, pipeline and filter bags to eliminate cross-contamination. Even trace foreign cathode powder will severely damage battery performance.
2. Replace atmosphere system: Switch from dry-air open circuit (LFP/LMO) to nitrogen closed-loop inert system for NCM/NCA.
3. Reset process parameters: classifier speed, gas flow, feed rate, temperature interlock thresholds.
4. Verify liner and wear parts: Ceramic liners are mandatory for all high-purity cathode grades. If carbon or metal wear parts are used for LFP, they cannot be used for NCM/NCA without upgrade.
5. Pre-run blank test: Run a small batch of new material and test impurity, PSD and electrochemical performance before formal production.

3. Key limiting factors preventing simple direct switching

1. Cross-contamination risk: Mixed cathode materials cause severe cell failure. This is the biggest barrier.
2. Atmosphere requirement gap: LFP/LMO can run on dry air; NCA / high-nickel NCM require nitrogen low-dew-point closed loop.
3. Heat management: ACM can run LFP/LMO easily, but high-nickel NCM/NCA needs temperature interlock and reduced frictional heat.
4. Impurity control: High-nickel materials demand ultra-low metal contamination; wear parts must be full ceramic.
5. Anti-re-agglomeration settings: Residual lithium and static behavior differ, requiring different static dissipation and dew-point settings.

4. Recommended industrial practice

• Best practice: Dedicated mill lines for high-nickel NCM/NCA, separate from LFP/LMO/LCO lines, to avoid costly full cleaning and cross-contamination risk.
• If only one mill is available: Process stable materials (LFP, LMO) first, then high-nickel materials last. Do not reverse the sequence, because residual high-nickel fines are very hard to remove and will contaminate LFP batches.

A single mill can technically process multiple cathode materials, but it requires full cleaning, atmosphere switching, parameter re-tuning and impurity validation when switching between different material types. Cross-contamination is the primary risk. For mass production, separate dedicated lines are preferred, especially for heat-sensitive high-nickel NCM and NCA.