Aramid dielectric co-polymer: from molecular engineering to roll-to-roll scalability for high-temperature capacitive energy storage

Abstract

Aromatic polymer films with high glass transition temperatures (Tg) exhibit superior thermal stability, making them ideal for high-temperature dielectric capacitors in advanced electrical and electronic systems. However, the leakage current can be intensified at high temperatures due to stronger π-electron delocalization, leading to energy loss and degrading capacitive performance. Here, we present a poly sulfonated aramid (PSA) derived from aramid by molecular engineering, with Tg > 300°C. Sulfone groups with a non-planar structure are introduced to break strong π-π conjugation and subsequently suppress intramolecular charge transfer. Moreover, their large dipole moments contribute to a high dielectric constant. To suppress intermolecular charge transfer, organic small molecules of triptycene (TE) are filled at an optimized content, breaking π-π stacking among PSA chains. The activation energy for trapped carriers is further increased, while the hopping distance is shortened. The PSA/TE all-organic film achieves an energy density (Ud) of 5.71 J·cm−3 at an efficiency exceeding 90% and a maximum Ud of 9.03 J·cm-3 at 150°C. Additionally, sulfone groups also aid self-healing by generating more gaseous products during pyrolysis. A roll-to-roll production line is established for continuously fabricating large-scale and high-quality PSA-based films, allowing for industrial potential for high-temperature capacitive energy storage.