Meaning
Mechanical load applied to an electrode sheet during the rolling compression process determines the final coating density and porosity of the active material. This process variable, known as calendering pressure, is adjusted during battery manufacturing to optimize the electronic conductivity and electrolyte wetting of the anode and cathode. The parameter is measured in force per unit width of the roll or as a calculated pressure applied to the electrode coating.
Electrode Compression
Compression reduces the thickness of the wet-coated film to meet strict cell dimension requirements. High calendering pressure increases the packing density of the active particles, which improves the volumetric energy density of the finished cell. However, excessive compression can damage the current collector foil or fracture the active material particles.
Electrolyte Penetration
Pore structure within the electrode controls the transport rate of lithium ions between the liquid electrolyte and the active material. If the calendering pressure is too high, the resulting low porosity restricts electrolyte penetration and increases internal resistance. Conversely, inadequate pressure leaves large voids that result in poor electrical contact between the active particles and the current collector.
Manufacturing Control
Production lines employ automated feedback loops to adjust the compression force in real time as the electrode web travels through the rollers. Variations in coating thickness require immediate changes in calendering pressure to maintain a uniform electrode density across the entire roll. Consistent density prevents localized current density spikes and reduces the probability of lithium plating during rapid charging cycles.
This precise control directly lowers reject rates on the factory floor and extends the cycle life of the assembled lithium-ion batteries.
