Sandwich structure-assisted significantly improved discharge energy density in linear polymer nanocomposites with high thermal stability

Abstract

The sandwich-structured barium titanate/poly(ether imide) (BT/PEI) nanocomposites are fabricated layer-by-layer, with outer two insulation layers (ILs) for high breakdown strength and a middle polarization layer (PL) for high dielectric constant, using solution casting technique. Consequently, the sandwich-structured BT/PEI nanocomposites with optimum BT NPs concentration in ILs and PL showed tremendously enhanced discharge energy density (Ue) of 5.7 J/cm3, which is ∼256% and ∼307% higher than the pristine PEI (with 1.6 J/cm3) and its single-layered counterpart, i.e., 9 wt.% BT/PEI (with 1.4 J/cm3), respectively. The similar sandwich structure also displayed a significantly higher discharge efficiency of ∼62% at very high electric field. In addition, the high-temperature hysteresis loops for optimal sandwich structure nanocomposites revealed considerably high-temperature endurance until 150 °C at 200 MV/m. The present work paves the way for using sandwich-structured linear nanocomposites in thermally stable energy storage devices.