▎ 摘　　要

Rising energy storage demands have accelerated the research to develop highly efficient dielectrics, such as polymer nanocomposites for capacitor applications. Herein, high energy and power density in dielectric composites via incorporating a large number of hetero-interfaces and microcapacitors driven by interfacial polarization for thin-film-based flexible polymer capacitors are demonstrated. The barium titanate (BT) nanoparticles (NPs) and graphene oxide (GO) nanosheets are selectively localizing in the outer and middle layers, respectively. The BT/polyvinylidene fluoride (PVDF) as a "hard layer" helps in blocking the propagation of the electrical tree. The strong interaction between GO and PVDF in the GO/PVDF layer improves the interfacial polarization through formation of microcapacitors. Also, the confinement of the conduction charges simultaneously enhances the dielectric constant and breakdown strength. Thus, the GO nanofillers to work as both "soft layer" and "hard layer" are designed, and the energy density is improved to 11.4 J cm(-3) at 3617 kV cm(-1), approximate to 650% higher than that of commercially available biaxially oriented polypropylene (BOPP). Also, an ultrafast discharge time of 0.37 mu s as compared to 2.8 mu s for BOPP is achieved. These attributes make NP-BaTiO3/nano-GO/PVDF trilayered capacitors a suitable and promising candidate for the next-generation flexible thin-film dielectric capacitors.