Significantly enhanced energy storage density and efficiency of sandwich polymer-based composite via doped MgO and TiO2 nanofillers

Polymer dielectric materials are attracting wide focus in electronics, but their low energy density limits miniaturization and intelligent application. In recent years, the sandwich-structured has offered an ideal way to enhance the energy storage performance of polymer materials. In this work, the symmetrically sandwich composite dielectrics were prepared, containing an outer layer of poly (vinylidene fluoride-trifluoro ethylene chlorofluoride)@titanium dioxide (P (VDF-TrFE-CFE)@TiO2) and an inner layer of poly (methyl methacrylate)@magnesium oxide (PMMA@MgO). The sandwich structure can combine the advantages of the excellent breakdown strength of PMMA and the superior polarization strength of P (VDF-TrFE-CFE). Moreover, TiO2 with a high dielectric constant further improves the polarization strength, and the insulation performance enhances by MgO with a large band gap. The experimental results show that 0.5-1-0.5 sandwich composite dielectric has the most excellent breakdown strength of 633.8 kV/mm, and a discharge energy density of 17.16 J/cm(3) with an efficiency of 70.1%. This work offers experimental guidance for the development of outstanding energy storage performance of polymer dielectric capacitors.