Enhanced dielectric and energy storage properties of BaTiO3 nanofiber/polyimide composites by controlling surface defects of BaTiO3 nanofibers

BaTiO3 (BT) nanofibers with different surface defects were prepared by electrospinning process through controlling the sintering atmospheres (Air, N-2 and H-2), and introduced into polyimide (PI) matrix to form composite films. The effects of different surface defects on dielectric and energy storage properties of PI composites were systematically investigated. The results showed that the fabricated composite films under a reducing (H-2) atmosphere exhibited excellent dielectric properties, compared with that under Air and O-2. The dielectric constant (epsilon(r)) of PI composite films with 20 wt% BT-fibers reached up to 17.6, while maintaining lower loss (tg delta = 0.006@ 100 kHz), which was about four times greater than that of pure PI (epsilon(r) = 4.1). When the content of BT-fiber was up to 15 wt%, the composite film exhibited a maximum energy storage density of U-e = 6.12 J/cm(3). These results provide an effective method to tune the dielectric and energy storage properties of ferroelectric/polymer composites.