High Energy Density in Poly(Vinylidene Fluoride‐Chlorotrifluoroethylene) Nanocomposite with Oriented Graphene Exfoliated with Assistance of Fluoro Hyperbranched Copolymer

Abstract

Although a polymer film capacitor releases a huge power density in pulse time, its electrical capability is limited by the low energy density for the embedded hybrid device. It is still a challenge to increase the energy density and retain high charge–discharge efficiency of the polymer film. High dielectric properties and high energy density are obtained in the uniaxial stretching poly(vinylidene fluoride‐chlorotrifluoroethylene) (P(VDF‐CTFE)) nanocomposite incorporated with few‐layer graphene, which is exfoliated with the assistance of a fluoro hyperbranched polyethylene‐graft‐poly(trifluoroethyl methacrylate) (HBPE‐g‐PTFEMA) copolymer via CH—π noncovalent interactions. The graphene/P(VDF‐CTFE) nanocomposite film is prepared via solution casting, and then, the in‐plane orientation of nanosheets is accomplished by uniaxial deformation. The relative content of the β phase reaches 96.0% in 0.8 vol% nanocomposite due to the combination of improved compatibility and the alignment of macromolecular chains. The energy density of a 0.1 vol% graphene/P(VDF‐CTFE) film achieves 9.5 J cm−3 as E = 400 MV m−1, which is attributed to the large‐content electroactive phase and interfacial polarization. The P(VDF‐CTFE) nanocomposite incorporated with aligned graphene exhibits a promising energy storage capability, which indicates that the orientation of nanosheets is an effective solution to enhance the energy density of the polymer film with large charge–discharge efficiency.