Improved Dielectric Permittivity and Energy Density of Layered Polymer Composites through the Incorporation of Ultralow Amounts of RGO@BTO Hybrid Nanosheets

Polymer dielectric composites are extensively used in modern electronic devices because of their extremely high power density. However, unfavorable coupling between breakdown strength and dielectric permittivity can make achieving high energy density a challenge. In this study, reduced graphene oxide @ barium titanate (RGO@BTO) hybrid nanosheets have been fabricated and utilized as fillers in the design of RGO@BTO/P(VDF-HFP) single-layer films. An increase in permittivity to 24.8@10 kHz, i.e., equivalent to 253% of the P(VDF-HFP) (∼9.8@10 kHz) matrix, has been achieved with only 1 wt % RGO@BTO nanofillers due to the formation of microcapacitors. Furthermore, the RGO@BTO/P(VDF-HFP) film is hot-pressed with a PEI film and a P(VDF-HFP) film, forming a trilayer structure. Consequently, this trilayer film displays a high breakdown strength of 478 kV/mm, a high energy density of 8.25 J/cm3, and a satisfactory efficiency of 64.3%. Thus, this study provides an efficient route for designing polymer composites that combine high energy density with high permittivity.