Calendering isn’t just about density—it’s about durability. Electrodes undergo extreme stress during cell assembly (e.g., slitting, winding) and operation (repeated lithiumion insertion/extraction). Without proper mechanical reinforcement, electrodes crack, shed active material, or swell, leading to rapid capacity fade. Modern calendering addresses these challenges through:

Peel Strength Enhancement: Compaction increases adhesion between the active layer and current collector (e.g., copper foil for anodes, aluminum for cathodes). Peel strength improvements of 30–50% prevent particle detachment during bending or vibration, a critical factor for electric vehicle batteries exposed to rough terrains .

Flexibility Retention: Paradoxically, denser electrodes can become brittle. Precisioncalibrated rollers balance compaction force to maintain electrode flexibility, allowing tight winding without fractures. For example, gradientpressure systems apply higher force at the core and lighter pressure at the edges, preserving structural resilience .

Swelling Suppression: High compaction density reduces void spaces where lithium dendrites or gas bubbles form during cycling. Tests show calendered NCM811 cathodes exhibit 40% less thickness expansion after 500 cycles compared to noncalendered counterparts .

Emerging techniques like laserassisted calendering further refine surface smoothness, eliminating burrs that could pierce separators and cause short circuits. This is particularly vital for nextgen solidstate batteries, where even micronscale imperfections jeopardize safety .