Multidimensional architecture of BaTiO3@Al2O3 nanofibers and BNNSs enables high energy storage performance of PVDF‐based composites

Abstract Polymer‐based composites with high energy storage density are essential for flexible dielectric capacitors. Herein, a series of poly(vinylidene fluoride) (PVDF)‐based nanocomposite films are prepared by incorporating multidimensional hybrid fillers composed of BaTiO 3 nanoparticles (BT NPs), Al 2 O 3 nanofibers (Al 2 O 3 NFs) and hexagonal boron nitride nanosheets (BNNSs), where BT NPs are embedded and homogeneously dispersed in Al 2 O 3 NFs using electrospinning technique. Benefiting from Al 2 O 3 and BNNSs with wide‐band gap and high thermal conductivity as well as BT with high dielectric constant, a prominent enhancement of dielectric constant, breakdown strength and thermal conductivity are achieved in BT@Al 2 O 3 ‐BNNSs/PVDF nanocomposite. As a consequence, the energy storage density of BT@Al 2 O 3 ‐BNNSs/PVDF nanocomposite reaches 13.1 J/cm 3 at 490.9 kV/mm, which is 3.2 times that of PVDF and approximately 2 times that of PVDF nanocomposites using only BT@Al 2 O 3 or BNNSs as fillers. This work highlights the synergistic effects of nanofillers with different characteristics, and provides a promising strategy for flexible dielectric materials towards energy storage application. Highlights Designed multidimensional fillers containing BaTiO 3 NPs, Al 2 O 3 NFs, and BNNSs. Co‐enhanced dielectric and thermal conductivity properties of PVDF composites. Excellent energy storage density of 13.1 J/cm 3 .