What is percolation threshold in conductive additives?

Percolation threshold is the minimum loading at which a conductive additive forms a continuous electronic network in a composite or electrode.   Below this threshold, conductivity increases slowly; above it, conductivity rises sharply.   For battery electrodes, a lower percolation threshold means higher energy density and lower inactive material content.

CNT vs carbon black: fundamental difference

Carbon black: contact-based conduction

Carbon black relies on particle-to-particle contact to form conductive paths.   Its low aspect ratio means a large amount is required to bridge gaps between active materials, leading to higher percolation thresholds and increased inactive mass.

CNT: network-based conduction

Carbon nanotubes form long-range conductive networks due to their high aspect ratio.   A small amount of CNT can span large distances within the electrode, dramatically reducing the percolation threshold compared with carbon black.

Typical percolation threshold comparison

• Carbon black: typically 1–3 wt%

• MWCNT: typically 0.5–1 wt%

• SWCNT: typically 0.02–0.2 wt%

Why percolation threshold matters in batteries

Lower percolation threshold directly translates into higher active material loading, improved rate capability, and better cycle stability.   This is especially important in high-energy-density lithium-ion batteries and advanced lead-acid systems.

Related Product

•      SWCNT Slurry – High-Conductivity CNT Dispersion