# Tensile Testing on Battery Thin Films > This case study explores the mechanical behavior of ultra-thin battery separator films and aluminum current collectors used in lithium-ion batteries. Using ASTM-compliant tensile testing with an Instron 68SC-5 and high-precision Instron AVE3 non-contact video extensometer, Covalent evaluated the tensile properties of a 25 µm multilayer PP–PE–PP separator film alongside a 12 µm aluminum current collector […] Source: https://covalent.com/resource-library/tensile-testing-on-battery-thin-films/ Updated: 2026-07-06T17:19:37+00:00 --- ![](https://spcdn.shortpixel.ai/spio/ret_img,q_cdnize,to_auto,s_webp:avif/covalent.com/wp-content/themes/covalent/assets/images/blog-default-banner.jpg) ![](https://spcdn.shortpixel.ai/spio/ret_img,q_cdnize,to_auto,s_webp:avif/covalent.com/wp-content/themes/covalent/assets/images/blog-mobile-banner.jpg) # Tensile Testing on Battery Thin Films ![Tensile Testing on Battery Thin Films](https://spcdn.shortpixel.ai/spio/ret_img,q_cdnize,to_auto,s_webp:avif/covalent.com/wp-content/uploads/2026/06/covalent-battery-separator-case-study-v1.png) Jun 30, 2026 This case study explores the [mechanical behavior](https://covalent.com/applications/mechanical-testing/) of ultra-thin battery separator films and aluminum current collectors used in lithium-ion batteries. Using ASTM-compliant tensile testing with an Instron 68SC-5 and high-precision Instron AVE3 non-contact video extensometer, Covalent evaluated the tensile properties of a 25 µm multilayer PP–PE–PP separator film alongside a 12 µm aluminum current collector foil. The study demonstrates how ultra-thin battery materials experience fundamentally different mechanical demands during winding, calendaring, slitting, and assembly operations. Stress–strain analysis revealed the separator film exhibited high ductility and flexibility, reaching approximately 56.6% strain at break, while the aluminum foil demonstrated significantly higher stiffness and strength but fractured at only ~0.85% strain. The results highlight the importance of accurately characterizing elastic modulus, yield stress, [tensile strength](https://covalent.com/techniques/mechanical-testing/tensile-testing/), and strain-to-failure in advanced battery materials as manufacturers continue pushing toward thinner, lighter, and higher-energy-density cell designs. The study also demonstrates the exceptional repeatability and precision achievable using modern non-contact strain measurement techniques for delicate thin-film battery materials. Subscribe to Our Newsletter Subscribe to our newsletter for the latest updates, insights, and breakthroughs - delivered straight to your inbox.