Meaning
Particle size distribution thresholds define the specific diameter below which ninety percent of the sample volume lies during laser diffraction measurements. The d90 parameter represents the coarse fraction of the battery powder, which limits the minimum possible coating thickness of the electrode. Large particles exceeding this threshold can scratch the foil during coating or cause localized stress points during the calendaring process.
Sourcing specifications mandate strict limits on this value to prevent short circuits.
Coarse Limit
Coarse particles within the distribution determine the maximum wet gap height of the coating slot die. Large grains create streaks or pinholes in the wet active layer.
Coating Quality
High d90 values require larger slot die openings, which increases the minimum wet thickness. This dependency prevents the production of ultra-thin electrode sheets for high-power cells.
Battery Safety
Calendaring forces large particles into the metal foil current collector, which can damage the separator. This damage creates pathways for dendrite growth and thermal runaway.
