Energy storage performance of sandwich structure composites with strawberry-like Ag@SrTiO3 nanofillers

Recent years witness a rapid surge in the research efforts on dielectric capacitors due to their high power density and fast charge/discharge speed. However, the relatively low energy density demands more efforts to meet the lightweight and compact requirement for practical applications. Here, we report sandwich-structured nanocomposite films with strawberry-like Ag@SrTiO 3 nanofillers. The introduction of Ag nanoparticles (NPs) on SrTiO 3 NPs could significantly improve dielectric properties, breakdown strength, energy storage density, and efficiency. As a result, a dramatically enhanced discharged energy density (24.6 J/cm 3 ) and efficiency (86.3%) are reached in sandwich-structured nanocomposite films containing 1.5 wt% Ag@SrTiO 3 nanofillers by the solution casting method. The enhancement of dielectric constant and breakdown strength of nanocomposite films is attributed to the Coulomb-blockade effect of Ag NPs, which inhibits the transformation of electrons. Our finite element simulation explicitly demonstrates that the Coulomb-blockade effect of Ag NPs can effectively improve energy storage performance, which therefore supports the experimental results.