Enhanced Energy Storage in PVDF-Based Nanocomposite Capacitors through (00l)-Oriented BaTiO₃ Single-Crystal Platelets

Flexible nanocomposite dielectrics with inorganic nanofillers exhibit great potential for energy storage devices in advanced microelectronics applications. However, high loading of inorganic nanofillers in the matrix results in an inhomogeneous electric field distribution, thereby hindering the improvement of the energy storage density (U_e) of the dielectrics. Herein, we proposed a strategy that utilized (00l)-oriented barium titanate (BT) single-crystal platelets to fabricate trilayered nanocomposite dielectrics for energy storage applications. The trilayered nanocomposites consisted of two high-permittivity layers of (Ta₂O₅, Al₂O₃) codoped TiO₂ nanoparticles (Ta-Al@TiO₂ nps) dispersed in a poly(vinylidene fluoride) (PVDF) matrix to facilitate large electric displacement and a middle layer of (00l)-oriented BT single-crystal platelets to provide high breakdown strength. Hence, the trilayered PVDF/Ta-Al@TiO₂ nps/BT single-crystal platelet nanocomposite film attains an outstanding U_e of 16.9 J cm^-3 at 370 kV mm^-1, which is ∼625% higher than that of the single-layer PVDF/Ta-Al@TiO₂ nps film. Finite element simulation further clarified that the successive inner layer of highly (00l)-oriented BT single-crystal platelets could effectively restrain the propagation of electrical treeing in trilayered nanocomposites. This research offers an effective approach for developing flexible dielectric capacitors with an excellent energy storage performance.