SiO 2 particle-supported ultrathin graphene hybrids/polyvinylidene fluoride composites with excellent dielectric performance and energy storage density

Polymer composites of polyvinylidene fluoride (PVDF) filled with SiO 2 –reduced graphene oxide (RGO) hybrids were fabricated and their dielectric properties and energy storage performance were systematically investigated. Hybrid SiO 2 –RGO with core-cell were prepared by using of SiO 2 particles as rigid template and the thermal reduction of the electrostatic assembled SiO 2 –GO hybrids, in which the inside rigid particles could support the uniform dispersion of ultrathin RGO sheets in the PVDF matrix and thus leading to a much lower percolation threshold (0.141 vol% for RGO in composite) than those of most reported graphene/polymer composites. Only a small amount of RGO in composites lead to high dielectric permittivity (72.94) and low dielectric loss (0.059) which should be ascribed to the increase of interfacial polarization between filler and matrix. More importantly, the composites with high breakdown strength (2438 kV/cm), energy density (0.301 J/cm 3 ) and charge–discharge efficiency (91.2%) can be achieved by incorporation of 10 wt% filler loading. This study provides a special pathway to ensure the dispersion and highly efficient usage of ultrathin graphene sheets in the polymer matrix and achieve graphene/polymer composite with excellent dielectric performance and energy storage density.