Achieving high discharged energy density in PVDF-based nanocomposites loaded with fine Ba0.6Sr0.4TiO3 nanofibers

Recently, research in advanced energy storage materials with enhanced performance to satisfy the rapid growth of modern microelectronics has drawn tremendous attention. Poly (vinylidene fluoride) (PVDF)-based nanocomposites loaded with one-dimensional inorganic nanofillers are one of the most extensive research systems. Higher discharged energy density could be obtained in dielectric capacitors with larger dielectric permittivity and higher breakdown strength. Herein, Ba 0.6 Sr 0.4 TiO 3 nanofibers (BST NFs) with three different diameters (NF1~140 nm, NF2~305 nm, NF3~505 nm) are fabricated by adjusting the parameters during the electrospinning process. The results suggest that optimizing the diameter and content of nanofibers is useful to form a balance between dielectric permittivity and the resistance to electrical breakdown . Nevertheless, discharged energy density ( U d ) as well as energy storage efficiency ( η ) turn down with thicker filler. The nanocomposite films loaded with a low content (1 vol%) of BST NF1 illustrates a large electric displacement of 10.4 μc/cm 2 at 575 MV/m and a rather high U d about 19.4 J/cm 3 compared with the U d (≈11.08 J/cm 3 at 475 MV/m) of pure PVDF film. More importantly, the discharge efficiency of the nanocomposites maintains a rather high level of 64%. Thus, regulating the diameter of 1D nanofillers could be a facile and effective option to obtain dielectric nanocomposite with outstanding energy storage performance. • BST nanofibers with various diameters were prepared by adjusting the parameters of the electrospinning processes. • The composites loaded with the finest BST NFs (~140 nm) exhibited excellent energy storage performance. • A novel strategy of reducing one-dimensional filler diameter to enhance energy storage density of composites was proposed.