High discharged energy density of polymer nanocomposites containing paraelectric SrTiO3 nanowires for flexible energy storage device

Nanocomposites combining high permittivity ferroelectric nanofillers and high breakdown strength polymer have shown tremendous potential for pulsed power applications. Nevertheless, the discharged energy density and efficiency of these nanocomposites filled with ferroelectric fillers are limited due to the large remanent polarization of ferroelectric fillers employed. Here, uniform elongated morphology paraelectric SrTiO3 nanowires fillers were synthesized via a special stirring hydrothermal method. The fabricated P(VDF-CTFE)-based nanocomposites containing 3 vol% paraelectric SrTiO3 nanowires exhibit an enhanced discharged energy density of 8.8 J/cm3 at 3381 kV/cm, which exceeds most of the current reports at the same electric field. By direct comparison study with ferroelectric BaTiO3 nanowires fillers, the results show paraelectric SrTiO3 nanowires can simultaneously improve the discharged energy density and efficiency more effectively. Such enhancement in energy storage performance can be attributed to the following reasons: (I) The enhanced breakdown strength, which resulted from the reduced inhomogeneous electric fields via adopting the SrTiO3 nanowires with lower permittivity. (II) The paraelectric phase SrTiO3 nanowires show little hysteresis behavior compared to ferroelectric phase BaTiO3 nanowires. This work is of critical significance in making advanced dielectric nanocomposites that are viable for energy storage devices in current electronic and electrical applications.