Mechanical Characterization of Single-Layer Ceramic-Coated Battery Separators and Finite Element Modeling of Their Deformation

Mechanical characterization of battery separators provides inputs for material-level finite element models. This study investigates components extracted from a commercial 37 Ah graphite/NMC pouch cell, focusing on single layers of an Al2O3-coated polyolefin separator conditioned in salt-free EC:DMC. Through-thickness compression of single layers is compared with 34-layer stacks and previously reported 100-layer data for the same separator and conditioning; both stack configurations show similar trends that differ from the single-layer response. Tensile tests characterize the machine and transverse and 45-degree directions, showing greater elongation at failure in the machine direction at broadly similar stress levels. Single-layer compression exhibits nonlinear loading and incomplete recovery during recorded unloading; these observations do not uniquely identify the underlying deformation mechanisms. The measured compression and principal-direction tensile responses support the parameterization of MAT_126 in LS-DYNA. Root-mean-square errors below 1.3% of the maximum stress quantify calibration agreement, not independent validation. The multilayer simulation provides insight into the internal stress distribution and possible factors contributing to differences between single-layer and stack compression responses. Together, the experimental characterization and material-level simulations highlight the value of single-layer testing for separator model calibration and provide a basis for further development of battery models for crash applications.