Largely enhanced discharge energy density in linear polymer nanocomposites by designing a sandwich structure

The development of flexible film dielectric capacitors with high discharge energy densities is of central significance for advanced electric and electronic power systems. Herein, a novel sandwich structure designed barium titanate/poly(methyl methacrylate) (BT/PMMA) nanocomposites are prepared layer-by-layer using solution casting method. The outer two layers with low BT nanoparticles concentration offered a considerably higher breakdown strength, while the central polarization layer with higher BT nanoparticles concentration presented higher dielectric constant to the nanocomposites. Consequently, 1-9-1 BT/PMMA nanocomposite compared to its single-layered counterpart (i.e. 9 wt% BT/PMMA) showed a ∼238% improvement in discharge energy density (i.e. from 1.8 J/cm3 to 6.08 J/cm3). The discharge rate analysis presented that 1-9-1 BT/PMMA discharges in 2.44 μs with a power density of about 0.5 MW/cm3 at a time constant (τ0.9). This work significantly paves the way for using sandwich-structured linear polymer nanocomposites in high energy density and fast discharge rate dielectrics application.