Enhanced capacitive energy storage performance induced by incorporating BaTiO₃ nanofibers in PEI-based multilayered nanocomposite films

Polymer-based composites are currently pivotal materials for achieving lightweight and integrated high-energy pulsed power systems. However, their broad application remains constrained by relatively low energy storage density and efficiency. In this study, we successfully fabricated BaTiO₃ nanofibers (BTNFs) modified polyetherimide (PEI)-based multilayered composites via electrospinning and tape casting techniques, where the outer layer of the composite contains an extremely low content (1 wt%) of BTNFs fillers, while the middle layer incorporates a higher concentration of BTNFs as variable components. This sandwich-structured enables the BTNFs/PEI composites to exhibit enhanced polarization behavior and improved breakdown strength. These enhancements are attributed to the high dielectric constant of BTNFs fillers and the formation of a locally optimized electric field, as confirmed by experimental results and simulations. Consequently, the optimized components achieved a high energy storage density of 16.65 J/cm³ and high energy efficiency of 92.60 %. Additionally, the composite material demonstrates excellent temperature stability and fatigue resistance in terms of energy storage performance. This research holds significant implications for enhancing the energy storage capabilities of polymer matrix composites through structural design.