Synthesis wide‐bandgap aluminum oxide decorated graphene for tailoring dielectric and energy storage properties of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) films

Abstract A composite dielectric film with synergistically improved dielectric constant ( ɛ ′) and breakdown strength ( E b ) was prepared by introducing wide‐bandgap aluminum oxide decorated reduced graphene oxide (rGO@Al 2 O 3 ) into poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) (P(VDF‐CTFE)). Consequently, a superior energy storage density ( U e = 3.6 J cm −3 ) of rGO@Al 2 O 3 /P(VDF‐CTFE) was obtained with only 0.1 wt% loading of rGO@Al 2 O 3 , being 133%, 947% higher than those of neat P(VDF‐CTFE) and 0.1 wt% rGO/P(VDF‐CTFE), respectively. These enhancements can be ascribed to the presence of core‐shell like rGO@Al 2 O 3 , where rGO effectively promotes surface polarization of composites, while Al 2 O 3 as a barrier provides deep traps and prevents the physical contact of rGO nanosheets, thus inhibiting local field concentration and limiting charge carrier transition. Highlights Wide‐bandgap Al 2 O 3 decorated rGO was introduced into P(VDF‐CTFE). The presence of Al 2 O 3 hinders charge carrier leakage of the composites. rGO@Al 2 O 3 increases the permittivity by forming plenty of micro‐capacitors. An improved energy storage density and efficiency are simultaneously achieved.