Damage evolution of metalized plastic current collectors induced by particle indentation during calendering

Metalized plastic current collectors (MPCCs) with metal layers deposited on both sides of an ultrathin polymer substrate are promising substitute for conventional metal current collectors to enhance safety and energy density of lithium-ion batteries (LIBs). However, large compression in the calendering process easily induces mechanical damage in MPCCs due to its poor mechanical properties, potentially increasing the failure risk of electrodes during subsequent battery assembly and cycling. Here, the damage evolution and mechanical-electrical failure mechanisms of Cu/PET MPCCs and Al/PET MPCCs under the calendering process are investigated. Experiments and finite element simulations show that the tensile component contributes marginally to calendering induced damage because of the small tensile strain during calendering. In contrast, the compression driven by active particles on MPCCs dominates the damage evolution, and leads to pronounced degradation in both mechanical and electrical performance. Cu/PET MPCCs mainly undergo localized plastic deformation at high compaction densities, whereas Al/PET MPCCs are prone to interfacial delamination due to the weak interfacial adhesion. Simulations further indicate that calendering induced defects increase the failure risk under the tensile loading from subsequent roll-to-roll winding. These findings provide mechanistic guidance for calendering parameter optimization and MPCC design.