Roll-to-Roll Scalable Manufacturing of Nanoporous Separators for High-Safety Lithium-Ion Batteries

The separator plays an essential role in the electrochemical and safety performance of lithium-ion batteries (LIBs). However, commercial polyolefin separators face challenges such as poor thermal resistance, unsatisfactory electrolyte wettability, and interfacial instability. Herein, we propose a scalable method to fabricate a nanoporous poly(m-phenylene isophthalamide) (PMIA)-modified polyethylene (PE) separator (PMIA@PE) using a nonsolvent and evaporation-induced phase separation technique. Life cycle assessment indicates that this method significantly reduces water consumption during production and has a lower environmental impact compared with the conventional wet method. The separator exhibits superior thermal stability, with shrinkage <6% after treatment at 210 °C for 1 h. Accelerating rate calorimetry tests show that 60 Ah LiNi_0.6Mn_0.2Co_0.2O₂/graphite pouch batteries with PMIA@PE have the highest thermal runaway (TR) trigger temperature, lowest TR peak temperature, and slowest temperature rise rate compared to commercial PE and Al₂O₃@PE separators. Moreover, PMIA@PE offers better electrolyte affinity and cycling stability without sacrificing specific capacity or rate capability. These high-performance separators and the resulting safe batteries show great promise for addressing TR risks in large-format LIBs for electric vehicles.