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@Al₂O₃) into poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) (P(VDF‐CTFE)). Consequently, a superior energy storage density (U_e = 3.6 J cm⁻³) of rGO@Al₂O₃/P(VDF‐CTFE) was obtained with only 0.1 wt% loading of rGO@Al₂O₃, 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@Al₂O₃, where rGO effectively promotes surface polarization of composites, while Al₂O₃ 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 Al₂O₃ decorated rGO was introduced into P(VDF‐CTFE). The presence of Al₂O₃ hinders charge carrier leakage of the composites. rGO@Al₂O₃ increases the permittivity by forming plenty of micro‐capacitors. An improved energy storage density and efficiency are simultaneously achieved.