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 BaTiO₃ nanoparticles (BT NPs), Al₂O₃ nanofibers (Al₂O₃ NFs) and hexagonal boron nitride nanosheets (BNNSs), where BT NPs are embedded and homogeneously dispersed in Al₂O₃ NFs using electrospinning technique. Benefiting from Al₂O₃ 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@Al₂O₃‐BNNSs/PVDF nanocomposite. As a consequence, the energy storage density of BT@Al₂O₃‐BNNSs/PVDF nanocomposite reaches 13.1 J/cm³ at 490.9 kV/mm, which is 3.2 times that of PVDF and approximately 2 times that of PVDF nanocomposites using only BT@Al₂O₃ 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 BaTiO₃ NPs, Al₂O₃ NFs, and BNNSs. Co‐enhanced dielectric and thermal conductivity properties of PVDF composites. Excellent energy storage density of 13.1 J/cm³.